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Hermanns M, Wehres N, Heyne B, Honingh CE, Graf UU, Schlemmer S. Performance of a chirped-pulse Fourier transform millimeter wave spectrometer in the range of 75-110 GHz. Rev Sci Instrum 2023; 94:034705. [PMID: 37012769 DOI: 10.1063/5.0141579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/21/2023] [Indexed: 06/19/2023]
Abstract
We present a home-built chirped-pulse Fourier transform millimeter wave (CP-FTMMW) spectrometer. The setup is devoted to the sensitive recording of high-resolution molecular spectroscopy in the W band between 75 and 110 GHz. We describe the experimental setup in detail, including a characterization of the chirp excitation source, the optical beam path, and the receiver. The receiver is a further development of our 100 GHz emission spectrometer. The spectrometer is equipped with a pulsed jet expansion and a DC discharge. Spectra of methyl cyanide as well as hydrogen cyanide (HCN) and hydrogen isocyanide (HNC) products from the DC discharge of this molecule are recorded to characterize the performance of the CP-FTMMW instrument. The formation of the HCN isomer is favored by a factor of 63 with respect to HNC. Hot/cold calibration measurements enable a direct comparison of the signal and noise levels of the CP-FTMMW spectra to those of the emission spectrometer. For the CP-FTMMW instrument, we find many orders of magnitude of signal enhancement and a much stronger noise reduction due to the coherent detection scheme.
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Affiliation(s)
- M Hermanns
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - N Wehres
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - B Heyne
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - C E Honingh
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - U U Graf
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - S Schlemmer
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
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Wehres N, Maßen J, Borisov K, Schmidt B, Lewen F, Graf UU, Honingh CE, Higgins DR, Schlemmer S. A laboratory heterodyne emission spectrometer at submillimeter wavelengths. Phys Chem Chem Phys 2018; 20:5530-5544. [PMID: 29168510 DOI: 10.1039/c7cp06394f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We present first results on a newly built broadband emission spectrometer for the laboratory making use of a double sideband (DSB) heterodyne receiver. The new spectrometer is perfectly suited for high-resolution emission spectroscopy of molecules of astrophysical importance. The current SIS receiver operates at RF frequencies between 270 and 390 GHz, coincident with Band 7 of the ALMA telescope. The instantaneous bandwidth is 5 GHz (DSB). In this work the full spectrometer and its components are described. Its performance, in particular its sensitivity, stability, reproducibility and systematic errors, is characterized in detail. For this purpose very broad band emission spectra of methyl cyanide have been recorded and compared to theoretical spectra. Isotopic variants are found in natural abundance and features attributed to vibrationally excited species are all recorded in the same spectrum. The performance of the new spectrometer is compared extensively to that of a traditional FM-absorption spectrometer and to recent versions of chirped-pulse spectrometers operated in the mm-wave regime. Further applications and future advancements of the current instrument are discussed.
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Affiliation(s)
- N Wehres
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, Köln, Germany.
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Surin LA, Tarabukin IV, Schlemmer S, Kalugina YN, van der Avoird A. Ab initio potential and rotational spectra of the CO–N2 complex. J Chem Phys 2018; 148:044313. [PMID: 29390838 DOI: 10.1063/1.5013115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- L. A. Surin
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 108840 Troitsk, Moscow, Russia
- I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
| | - I. V. Tarabukin
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 108840 Troitsk, Moscow, Russia
| | - S. Schlemmer
- I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
| | - Y. N. Kalugina
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 108840 Troitsk, Moscow, Russia
- Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin Ave., 634050 Tomsk, Russia
| | - A. van der Avoird
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Surin LA, Tarabukin IV, Panfilov VA, Schlemmer S, Kalugina YN, Faure A, Rist C, van der Avoird A. Rotational study of the CH4–CO complex: Millimeter-wave measurements and ab initio calculations. J Chem Phys 2015; 143:154303. [DOI: 10.1063/1.4933061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- L. A. Surin
- I. Physikalisches Institut, University of Cologne, Zülpicher St. 77, 50937 Cologne, Germany
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya St. 5, 142190 Troitsk, Moscow, Russia
| | - I. V. Tarabukin
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya St. 5, 142190 Troitsk, Moscow, Russia
| | - V. A. Panfilov
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya St. 5, 142190 Troitsk, Moscow, Russia
| | - S. Schlemmer
- I. Physikalisches Institut, University of Cologne, Zülpicher St. 77, 50937 Cologne, Germany
| | - Y. N. Kalugina
- Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin Ave., 634050 Tomsk, Russia
| | - A. Faure
- University Grenoble Alpes, IPAG, F-38000 Grenoble, France
- CNRS, IPAG, F-38000 Grenoble, France
| | - C. Rist
- University Grenoble Alpes, IPAG, F-38000 Grenoble, France
- CNRS, IPAG, F-38000 Grenoble, France
| | - A. van der Avoird
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Wakelam V, Loison JC, Herbst E, Pavone B, Bergeat A, Béroff K, Chabot M, Faure A, Galli D, Geppert WD, Gerlich D, Gratier P, Harada N, Hickson KM, Honvault P, Klippenstein SJ, Picard SDL, Nyman G, Ruaud M, Schlemmer S, Sims IR, Talbi D, Tennyson J, Wester R. THE 2014 KIDA NETWORK FOR INTERSTELLAR CHEMISTRY. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0067-0049/217/2/20] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Surin LA, Potapov A, Dolgov AA, Tarabukin IV, Panfilov VA, Schlemmer S, Kalugina YN, Faure A, van der Avoird A. Rotational study of the NH3–CO complex: Millimeter-wave measurements and ab initio calculations. J Chem Phys 2015; 142:114308. [DOI: 10.1063/1.4915119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- L. A. Surin
- I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia
| | - A. Potapov
- I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
| | - A. A. Dolgov
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia
| | - I. V. Tarabukin
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia
| | - V. A. Panfilov
- Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia
| | - S. Schlemmer
- I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany
| | - Y. N. Kalugina
- Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin av., 634050 Tomsk, Russia
| | - A. Faure
- Université de Grenoble Alpes, IPAG, F-38000 Grenoble, France
- CNRS, IPAG, F-38000 Grenoble, France
| | - A. van der Avoird
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Jankowski P, Surin LA, Potapov A, Schlemmer S, McKellar ARW, Szalewicz K. A comprehensive experimental and theoretical study of H2−CO spectra. J Chem Phys 2013; 138:084307. [PMID: 23464151 DOI: 10.1063/1.4791712] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Piotr Jankowski
- Department of Quantum Chemistry, Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Toruń, Poland
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Xu LH, Lees RM, Crabbe GT, Myshrall JA, Müller HSP, Endres CP, Baum O, Lewen F, Schlemmer S, Menten KM, Billinghurst BE. Terahertz and far-infrared synchrotron spectroscopy and global modeling of methyl mercaptan, CH3(32)SH. J Chem Phys 2013; 137:104313. [PMID: 22979865 DOI: 10.1063/1.4745792] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, terahertz and Fourier transform far-infrared (FTFIR) synchrotron spectra of methyl mercaptan, CH(3)SH, have been investigated in order to provide new laboratory information for enhanced observations of this species in interstellar molecular clouds and star-forming regions. Like its methanol cousin, methyl mercaptan has particularly rich spectra associated with its large-amplitude internal rotation that extend throughout the THz and FIR regions. We have recorded new spectra for CH(3)SH from 1.1-1.5 and 1.790-1.808 THz at the University of Cologne as well as high-resolution FTFIR synchrotron spectra from 50-550 cm(-1) at 0.001 cm(-1) resolution on the far-IR beam-line at the Canadian Light Source. Assignments are reported for rotational quantum numbers up to J ≈ 40 and K ≈ 15, and torsional states up to v(t) = 2 for the THz measurements and v(t) = 3 for the FTFIR observations. The THz and FTFIR measurements together with literature results have been combined in a global analysis of a dataset comprising a total of 1725 microwave and THz frequencies together with ~18000 FTFIR transitions, ranging up to v(t) = 2 and J(max) = 30 for MW∕THz and 40 for FTFIR. The global fit employs 78 torsion-rotation parameters and has achieved a weighted standard deviation of ~1.1. A prediction list (v(t) ≤ 2, J ≤ 45 and K ≤ 20) has been generated from the model giving essentially complete coverage of observable CH(3)(32)SH transitions within the bandwidths of major new astronomical facilities such as HIFI (Heterodyne Instrument for the Far Infrared) on the Herschel Space Observatory, ALMA (Atacama Large Millimeter Array), SOFIA (Stratospheric Observatory For Infrared Astronomy) and APEX (Atacama Pathfinder Experiment) to close to spectroscopic accuracy.
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Affiliation(s)
- Li-Hong Xu
- Centre for Laser, Atomic and Molecular Physics, Department of Physics, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada.
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Krieg J, Klemann A, Gottbehüt I, Thorwirth S, Giesen TF, Schlemmer S. A continuous-wave optical parametric oscillator around 5-μm wavelength for high-resolution spectroscopy. Rev Sci Instrum 2011; 82:063105. [PMID: 21721672 DOI: 10.1063/1.3596569] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a continuous-wave optical parametric oscillator (OPO) capable of high resolution spectroscopy at wavelengths between 4.8 μm and 5.4 μm. It is based on periodically poled lithium niobate (PPLN) and is singly resonant for the signal radiation around 1.35 μm. Because of the strong absorption of PPLN at wavelengths longer than 4.5 μm, the OPO threshold rises to the scale of several watts, while it produces idler powers of more than 1 mW and offers continuous tuning over 15 GHz. A supersonic jet spectrometer is used in combination with the OPO to perform measurements of the transient linear molecule Si(2)C(3) at 1968.2 cm(-1). Fifty rovibrational transition frequencies of the ν(3) antisymmetric stretching mode have been determined with an accuracy on the order of 10(-4) cm(-1), and molecular parameters for the ground and the v(3) = 1 state have been determined most precisely.
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Affiliation(s)
- J Krieg
- I. Physikalisches Institut, Universität Köln, Zülpicher Str. 77, 50937 Köln, Germany.
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Krieg J, Lutter V, Hardy FX, Schlemmer S, Giesen TF. The ν5 antisymmetric stretching mode of linear C7 revisited in high resolution. J Chem Phys 2010; 132:224306. [DOI: 10.1063/1.3431964] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Raston PL, Xu Y, Jäger W, Potapov AV, Surin LA, Dumesh BS, Schlemmer S. Rotational study of carbon monoxide isotopologues in small 4He clusters. Phys Chem Chem Phys 2010; 12:8260-7. [DOI: 10.1039/c0cp00193g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Surin LA, Potapov AV, Dumesh BS, Schlemmer S, Xu Y, Raston PL, Jäger W. Rotational study of carbon monoxide solvated with helium atoms. Phys Rev Lett 2008; 101:233401. [PMID: 19113549 DOI: 10.1103/physrevlett.101.233401] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Indexed: 05/27/2023]
Abstract
High resolution microwave and millimeter-wave spectra of HeN-CO clusters with N up to 10, produced in a molecular expansion, were observed. Two series of J = 1-0 transitions were detected, which correspond to the a-type and b-type J = 1-0 transitions of He1-CO. The B rotational constant initially decreases with N and reaches a minimum at N = 3. Its subsequent rise indicates the transition from a molecular complex to a quantum solvated system already for N = 4. For N > or =6, the B value becomes larger than that of He1-CO, indicating an almost free rotation of CO within the helium environment.
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Affiliation(s)
- L A Surin
- I. Physikalisches Institut, University of Cologne, 50937 Cologne, Germany
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14
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Neubauer-Guenther P, Giesen TF, Schlemmer S, Yamada KMT. High resolution infrared spectra of the linear carbon cluster C7: The ν4 stretching fundamental band and associated hot bands. J Chem Phys 2007; 127:014313. [PMID: 17627352 DOI: 10.1063/1.2749520] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High resolution infrared spectra of the nu(4) fundamental antisymmetric stretching mode and associated hot bands of the linear carbon cluster C(7) were recorded using a tunable diode laser spectrometer in the frequency range of 2135-2141 cm(-1). Spectra of the nu(4) fundamental, nu(4)+nu(11)-nu(11), nu(4)+2nu(11)-2nu(11), and nu(4)+nu(8)-nu(8), bands have been analyzed and are compared to recent experimental results and high level ab initio calculations. In particular, the presented results give experimental evidence for the rigidity of C(7) and confirm theoretical predictions of a rather regular chain molecule, similar to the cases of C(4), C(5), and C(9). For the two energetically low-lying bending modes, nu(8) and nu(11), the rotational constants differ by less than 0.2%, from the ground state value, B(0)=0.030 624 4(28) cm(-1), in good agreement with the recent calculations by Botschwina [Chem. Phys. Lett. 354, 148 (2002)]. From the hot band analysis and the [script-l]-type doubling constant q, experimental values for the band origins of the nu(8) and nu(11) fundamentals have been derived.
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Endres CP, Lewen F, Giesen TF, Schlemmer S, Paveliev DG, Koschurinov YI, Ustinov VM, Zhucov AE. Application of superlattice multipliers for high-resolution terahertz spectroscopy. Rev Sci Instrum 2007; 78:043106. [PMID: 17477648 DOI: 10.1063/1.2722401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Frequency multipliers based on superlattice (SL) devices as nonlinear elements have been developed as radiation sources for a terahertz (THz) laboratory spectrometer. Input frequencies of 100 and 250 GHz from backward wave oscillators have been multiplied up to the 11th harmonic, producing usable frequencies up to 2.7 THz. Even at these high frequencies the output power is sufficient for laboratory spectroscopy. Comparisons to conventional high-resolution microwave spectroscopy methods reveal several superior features of this new device such as very high line frequency accuracies, broadband tunability, high output power levels at odd harmonics of the input frequency up to high orders, and a robust applicability.
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Affiliation(s)
- C P Endres
- I. Physikalisches Institut, Universtität zu Köln, Köln, Germany.
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Müller HSP, McCarthy MC, Bizzocchi L, Gupta H, Esser S, Lichau H, Caris M, Lewen F, Hahn J, Degli Esposti C, Schlemmer S, Thaddeus P. Rotational spectroscopy of the isotopic species of silicon monosulfide, SiS. Phys Chem Chem Phys 2007; 9:1579-86. [PMID: 17429551 DOI: 10.1039/b618799d] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pure rotational transitions of silicon monosulfide ((28)Si(32)S) and its rare isotopic species have been observed in their ground as well as vibrationally excited states by employing Fourier transform microwave (FTMW) spectroscopy of a supersonic molecular beam at centimetre wavelengths (13-37 GHz) and by using long-path absorption spectroscopy at millimetre and submillimetre wavelengths (127-925 GHz). The latter measurements include 91 transition frequencies for (28)Si(32)S, (28)Si(33)S, (28)Si(34)S, (29)Si(32)S and (30)Si(32)S in upsilon = 0, as well as 5 lines for (28)Si(32)S in upsilon = 1, with rotational quantum numbers J''< or = 52. The centimetre-wave measurements include more than 300 newly recorded lines. Together with previous data they result in almost 600 transitions (J'' = 0 and 1) from all twelve possible isotopic species, including (29)Si(36)S and (30)Si(36)S, which have fractional abundances of about 7 x 10(-6) and 4.5 x 10(-6), respectively. Rotational transitions were observed from upsilon = 0 for the least abundant isotopic species to as high as upsilon = 51 for the main species. Owing to the high spectral resolution of the FTMW spectrometer, hyperfine structure from the nuclear electric quadrupole moment of (33)S was resolved for species containing this isotope, as was much smaller nuclear spin-rotation splitting for isotopic species involving (29)Si. By combining the measurements here with previously published microwave and infrared data in one global fit, an improved set of spectroscopic parameters for SiS has been derived which include several terms describing the breakdown of the Born-Oppenheimer approximation. With this parameter set, highly accurate rotational frequencies for this important astronomical molecule can now be predicted well into the terahertz region.
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Affiliation(s)
- H S P Müller
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937, Köln, Germany.
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Surin LA, Fourzikov DN, Giesen TF, Schlemmer S, Winnewisser G, Panfilov VA, Dumesh BS, Vissers GWM, van der Avoird A. Isotope effects in the CO dimer: Millimeter wave spectrum and rovibrational calculations of (C12O18)2. J Chem Phys 2006; 125:094304. [PMID: 16965077 DOI: 10.1063/1.2345202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The millimeter wave spectrum of the isotopically substituted CO dimer, (12C18O)2, was studied with the Orotron jet spectrometer, confirming and extending a previous infrared study [A. R. W. McKellar, J. Mol. Spectrosc. 226, 190 (2004)]. A very dilute gas mixture of CO in Ne was used, which resulted in small consumption of 12C18O sample gas and produced cold and simple spectra. Using the technique of combination differences together with the data from the infrared work, six transitions in the 84-127 GHz region have been assigned. They belong to two branches, which connect four low levels of A+ symmetry to three previously unknown levels of A- symmetry. The discovery of the lowest state of A- symmetry, which corresponds to the projection K=0 of the total angular momentum J onto the intermolecular axis, identifies the geared bending mode of the 12C18O dimer at 3.607 cm(-1). Accompanying rovibrational calculations using a recently developed hybrid potential from ab initio coupled cluster [CCSD(T)] and symmetry-adapted perturbation theory calculations [G. W. M. Vissers et al., J. Chem. Phys. 122, 054306 (2005)] gave very good agreement with experiment. The isotopic dependence of the A+/A- energy splitting, the intermolecular separation R, and the energy difference of two ground state isomers, which change significantly when 18O or 13C are substituted into the normal (12C16O)2 isotopolog [L. A. Surin et al., J. Mol. Spectrosc. 223, 132 (2004)], was explained by these calculations. It turns out that the change in anisotropy of the intermolecular potential with respect to the shifted monomer centers of mass is particularly significant.
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Affiliation(s)
- L A Surin
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Cologne, Germany
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Surin L, Potapov A, Müller H, Panfilov V, Dumesh B, Giesen T, Schlemmer S. Millimeter-wave study of the CO–N2 van der Waals complex: new measurements of CO–orthoN2 and assignments of new states of CO–paraN2. J Mol Struct 2006. [DOI: 10.1016/j.molstruc.2006.02.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Grimm M, Langer B, Schlemmer S, Lischke T, Becker U, Widdra W, Gerlich D, Flesch R, Rühl E. Charging mechanisms of trapped element-selectively excited nanoparticles exposed to soft x rays. Phys Rev Lett 2006; 96:066801. [PMID: 16606027 DOI: 10.1103/physrevlett.96.066801] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Indexed: 05/08/2023]
Abstract
Charging mechanisms of trapped, element-selectively excited free SiO2 nanoparticles by soft x rays are reported. The absolute charge state of the particles is measured and the electron emission probability is derived. Changes in electron emission processes as a function of photon energy and particle charge are obtained from the charging current. This allows us to distinguish contributions from primary photoelectrons, Auger electrons, and secondary electrons. Processes leading to no change in charge state after absorption of x-ray photons are identified. O 1s-excited SiO2 particles of low charge state indicate that the charging current follows the inner-shell absorption. In contrast, highly charged SiO2 nanoparticles are efficiently charged by resonant Auger processes, whereas direct photoemission and normal Auger processes do not contribute to changes in particle charge. These results are discussed in terms of an electrostatic model.
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Affiliation(s)
- M Grimm
- Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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Asvany O, Giesen T, Redlich B, Schlemmer S. Experimental determination of the nu5 cis-bending vibrational frequency and Renner-Teller structure in ground state (X2Piu) C2H2+ using laser induced reactions. Phys Rev Lett 2005; 94:073001. [PMID: 15783811 DOI: 10.1103/physrevlett.94.073001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Indexed: 05/24/2023]
Abstract
The spectrum of the nu(5) cis-bending vibration of ground state (X(2)Pi(u)) C(2)H(2)(+) has been recorded applying the method of laser induced reactions in a low-temperature 22-pole ion trap. It is obtained by counting the number of products of the reaction C(2)H(2)(+) (v(5) = 1) + H(2)--> C(2)H(3)(+) + H as a function of the laser wavelength. The vibronic transitions Delta-Pi and Sigma-Pi with their corresponding spin-orbit and Renner-Teller substructure have been observed. Using a perturbative analysis, the vibrational frequency has been determined to omega(5) = (710 +/- 4) cm(-1) and the Renner-Teller parameter epsilon(5) is on the order of 3 x 10(-2).
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Affiliation(s)
- O Asvany
- Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands
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Asvany O, Savić I, Schlemmer S, Gerlich D. Variable temperature ion trap studies of CH4++H2, HD and D2: negative temperature dependence and significant isotope effect. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2003.11.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Wang YS, Tsai CH, Lee YT, Chang HC, Jiang JC, Asvany O, Schlemmer S, Gerlich D. Investigations of Protonated and Deprotonated Water Clusters Using a Low-Temperature 22-Pole Ion Trap. J Phys Chem A 2003. [DOI: 10.1021/jp022156m] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | | | | | | | - J. C. Jiang
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 106, ROC
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Schlemmer S, Luca A, Glosik J, Gerlich D. Temperature dependence of ternary rate coefficients for the (CO)n−1++2CO⇌(CO)n++CO reaction, and the role of isomers for the growth of larger (CO)n+ clusters. J Chem Phys 2002. [DOI: 10.1063/1.1451247] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Faubel M, Schlemmer S. A variable temperature bolometer for determining particle energy and absolute flux in molecular beams. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3735/21/1/013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Cook DJ, Schlemmer S, Balucani N, Wagner DR, Harrison JA, Steiner B, Saykally RJ. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers. J Phys Chem A 1998; 102:1465-81. [PMID: 11542815 DOI: 10.1021/jp9724434] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.
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Affiliation(s)
- D J Cook
- Department of Chemistry, University of California, Berkeley 94720-1460, USA
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Haufler E, Schlemmer S, Gerlich D. Absolute Integral and Differential Cross Sections for the Reactive Scattering of H- + D2 and D- + H2. J Phys Chem A 1997. [DOI: 10.1021/jp9707246] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- E. Haufler
- Institut für Physik, Gasentladungs- und Ionenphysik, TU Chemnitz, 09107 Chemnitz, F. R. Germany
| | - S. Schlemmer
- Institut für Physik, Gasentladungs- und Ionenphysik, TU Chemnitz, 09107 Chemnitz, F. R. Germany
| | - D. Gerlich
- Institut für Physik, Gasentladungs- und Ionenphysik, TU Chemnitz, 09107 Chemnitz, F. R. Germany
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Abstract
Interstellar dust is responsible, through surface reactions, for the creation of molecular hydrogen, the main component of the interstellar clouds in which new stars form. Intermediate between small, gas-phase molecules and dust are the polycyclic aromatic hydrocarbons (PAHs). Such molecules could account for 2-30% of the carbon in the Galaxy, and may provide nucleation sites for the formation of carbonaceous dust. Although PAHs have been proposed as the sources of the unidentified infrared emission bands that are observed in the spectra of a variety of interstellar sources, the emission characteristics of such molecules are still poorly understood. Here we report laboratory emission spectra of several representative PAHs, obtained in conditions approximating those of the interstellar medium, and measured over the entire spectral region spanned by the unidentified infrared bands. We find that neutral PAHs of small and moderate size can at best make only a minor contribution to these emission bands. Cations of these molecules, as well as much larger PAHs and their cations, remain viable candidates for the sources of these bands.
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Affiliation(s)
- D J Cook
- Department of Chemistry, University of California, Berkeley 94720-1460, USA
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Abstract
Infrared emission spectra of gas-phase naphthalene and pyrene have been measured in the range of 3 to 7.5 micrometers with ultraviolet laser desorption-excitation and a spectroscopic technique featuring single-photon counting in the infrared. The spectra were compared with the unidentified infrared emission bands that are observed in many astronomical objects. Marked discrepancies between those observations and the laboratory emission spectra in the wavelengths and relative intensities of principal spectral features led to the conclusion that small neutral unsubstituted polycyclic aromatic hydrocarbons cannot be the carriers of the unidentified infrared emission bands.
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Affiliation(s)
- S Schlemmer
- Department of Chemistry, University of California, Berkeley 94720-1460, USA
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Faubel M, Rusin L, Schlemmer S, Sondermann F, Tappe U, Toennies JP. A high resolution crossed molecular beam investigation of the absolute cross sections and product rotational states for the reaction F+D2(vi=0;ji=0,1)→DF(vf;jf)+D. J Chem Phys 1994. [DOI: 10.1063/1.467718] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Trippett T, Schlemmer S, Elisseyeff Y, Goker E, Wachter M, Steinherz P, Tan C, Berman E, Wright JE, Rosowsky A. Defective transport as a mechanism of acquired resistance to methotrexate in patients with acute lymphocytic leukemia. Blood 1992; 80:1158-62. [PMID: 1381235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Although the mechanisms of resistance to methotrexate (MTX) are known in experimental tumors made resistant to this drug, little information is available regarding acquired resistance to MTX in patients. A competitive displacement assay using the fluorescent lysine analogue of MTX, N-(4-amino-4-deoxy-N10-methylpteroyl)-N epsilon-(4'-fluorescein-thiocarbamyl)-L-lysine (PT430), was developed as a sensitive method of detection of transport resistance to MTX in cell lines, as well as in blast cells from patients with leukemia. Rapid uptake of PT430 at high concentrations (20 mumol/L) in leukemic blasts resulted in achievement of steady-state levels within 2 hours. Subsequent incubation with the folate antagonists, MTX and trimetrexate (TMTX), which differ in the mode of carrier transport, produced characteristic patterns of PT430 displacement. Flow cytometric analysis of the mean fluorescence intensity in the human CCRF-CEM T-cell lymphoblastic leukemia cell line and its MTX-resistant subline clearly identified the presence of transport deficiency in the resistant subline. Analysis of blasts from 17 patients with leukemia, nine with no prior chemotherapy and eight previously treated with chemotherapy, found evidence of MTX transport resistance in two of the four patients who were treated with MTX and considered to be clinically resistant to the drug. The finding that blast cells of some patients with leukemia considered clinically resistant to MTX is due to decreased MTX transport has important implications for clinical use of this drug and for new drug development.
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Affiliation(s)
- T Trippett
- Program of Molecular Pharmacology and Therapeutics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021
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Grin W, Wierrani F, Ogris H, Grünberger W, Angerer A, Hiess T, Marian A, Razek G, Schlemmer S, Tomaschek C. [Computer-assisted patient management. Individual electronic data processing-assisted documentation in gynecology]. Gynakol Geburtshilfliche Rundsch 1992; 32:151-4. [PMID: 1467658 DOI: 10.1159/000271871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
EDP-supported documentation of patients has become increasingly important over the last several years. Seven autonomous wards of the gynecological department of the Hospital Rudolfstiftung were equipped with a clinical documentation system. The integration of this new system into the infrastructure of the KIS (Krankenhausinformationssystem) was accomplished with the help of the MD-ADV. We also implemented one of the best-known statistical analyzing systems, SAS, so that we have simple possibilities for statistical calculation and graphical plots.
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Affiliation(s)
- W Grin
- Abteilung für Gynäkologie und Geburtshilfe Krankenhaus Rudolfstiftung der Stadt Wien, Osterreich
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Faubel M, Schlemmer S, Sondermann F, Toennies JP. High resolution time‐of‐flight spectra for reactive scattering of F+D2. J Chem Phys 1991. [DOI: 10.1063/1.460599] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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