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Abassi L, Bertoglio F, Mačak Šafranko Ž, Schirrmann T, Greweling-Pils M, Seifert O, Khan F, Katzmarzyk M, Jacobsen H, Gödecke N, Heine PA, Frenzel A, Nowack H, Dübel S, Kurolt IC, Kontermann RE, Markotić A, Schubert M, Hust M, Čičin-Šain L. Evaluation of the Neutralizing Antibody STE90-C11 against SARS-CoV-2 Delta Infection and Its Recognition of Other Variants of Concerns. Viruses 2023; 15:2153. [PMID: 38005829 PMCID: PMC10675157 DOI: 10.3390/v15112153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 10/18/2023] [Accepted: 10/21/2023] [Indexed: 11/26/2023] Open
Abstract
As of now, the COVID-19 pandemic has spread to over 770 million confirmed cases and caused approximately 7 million deaths. While several vaccines and monoclonal antibodies (mAb) have been developed and deployed, natural selection against immune recognition of viral antigens by antibodies has fueled the evolution of new emerging variants and limited the immune protection by vaccines and mAb. To optimize the efficiency of mAb, it is imperative to understand how they neutralize the variants of concern (VoCs) and to investigate the mutations responsible for immune escape. In this study, we show the in vitro neutralizing effects of a previously described monoclonal antibody (STE90-C11) against the SARS-CoV-2 Delta variant (B.1.617.2) and its in vivo effects in therapeutic and prophylactic settings. We also show that the Omicron variant avoids recognition by this mAb. To define which mutations are responsible for the escape in the Omicron variant, we used a library of pseudovirus mutants carrying each of the mutations present in the Omicron VoC individually. We show that either 501Y or 417K point mutations were sufficient for the escape of Omicron recognition by STE90-C11. To test how escape mutations act against a combination of antibodies, we tested the same library against bispecific antibodies, recognizing two discrete regions of the spike antigen. While Omicron escaped the control by the bispecific antibodies, the same antibodies controlled all mutants with individual mutations.
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Affiliation(s)
- Leila Abassi
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
| | - Federico Bertoglio
- Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany; (F.B.); (P.A.H.); (S.D.); (M.S.); (M.H.)
| | - Željka Mačak Šafranko
- Research Department, University Hospital for Infectious Diseases “Dr. Fran Mihaljević”, 10000 Zagreb, Croatia; (Ž.M.Š.); (I.-C.K.); (A.M.)
| | - Thomas Schirrmann
- YUMAB GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany; (T.S.); (A.F.)
| | - Marina Greweling-Pils
- Core Facility of Comparative Medicine, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany;
| | - Oliver Seifert
- Institute of Cell Biology and Immunology, University of Stuttgart, 70174 Stuttgart, Germany; (O.S.); (H.N.); (R.E.K.)
| | - Fawad Khan
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
| | - Maeva Katzmarzyk
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
| | - Henning Jacobsen
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
| | - Natascha Gödecke
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
| | - Philip Alexander Heine
- Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany; (F.B.); (P.A.H.); (S.D.); (M.S.); (M.H.)
| | - André Frenzel
- YUMAB GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany; (T.S.); (A.F.)
| | - Helena Nowack
- Institute of Cell Biology and Immunology, University of Stuttgart, 70174 Stuttgart, Germany; (O.S.); (H.N.); (R.E.K.)
| | - Stefan Dübel
- Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany; (F.B.); (P.A.H.); (S.D.); (M.S.); (M.H.)
| | - Ivan-Christian Kurolt
- Research Department, University Hospital for Infectious Diseases “Dr. Fran Mihaljević”, 10000 Zagreb, Croatia; (Ž.M.Š.); (I.-C.K.); (A.M.)
| | - Roland E. Kontermann
- Institute of Cell Biology and Immunology, University of Stuttgart, 70174 Stuttgart, Germany; (O.S.); (H.N.); (R.E.K.)
| | - Alemka Markotić
- Research Department, University Hospital for Infectious Diseases “Dr. Fran Mihaljević”, 10000 Zagreb, Croatia; (Ž.M.Š.); (I.-C.K.); (A.M.)
- School of Medicine, Catholic University of Croatia, 10000 Zagreb, Croatia
- Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia
| | - Maren Schubert
- Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany; (F.B.); (P.A.H.); (S.D.); (M.S.); (M.H.)
| | - Michael Hust
- Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany; (F.B.); (P.A.H.); (S.D.); (M.S.); (M.H.)
| | - Luka Čičin-Šain
- Department of Viral Immunology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany; (L.A.); (F.K.); (M.K.); (H.J.); (N.G.)
- Centre for Individualized Infection Medicine, a Joint Venture of HZI and MHH, 31625 Hannover, Germany
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Sitnik KM, Krstanović F, Gödecke N, Rand U, Kubsch T, Maaß H, Kim Y, Brizić I, Čičin-Šain L. Fibroblasts are a site of murine cytomegalovirus lytic replication and Stat1-dependent latent persistence in vivo. Nat Commun 2023; 14:3087. [PMID: 37248241 DOI: 10.1038/s41467-023-38449-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 04/29/2023] [Indexed: 05/31/2023] Open
Abstract
To date, no herpesvirus has been shown to latently persist in fibroblastic cells. Here, we show that murine cytomegalovirus, a β-herpesvirus, persists for the long term and across organs in PDGFRα-positive fibroblastic cells, with similar or higher genome loads than in the previously known sites of murine cytomegalovirus latency. Whereas murine cytomegalovirus gene transcription in PDGFRα-positive fibroblastic cells is almost completely silenced at 5 months post-infection, these cells give rise to reactivated virus ex vivo, arguing that they support latent murine cytomegalovirus infection. Notably, PDGFRα-positive fibroblastic cells also support productive virus replication during primary murine cytomegalovirus infection. Mechanistically, Stat1-deficiency promotes lytic infection but abolishes latent persistence of murine cytomegalovirus in PDGFRα-positive fibroblastic cells in vivo. In sum, fibroblastic cells have a dual role as a site of lytic murine cytomegalovirus replication and a reservoir of latent murine cytomegalovirus in vivo and STAT1 is required for murine cytomegalovirus latent persistence in vivo.
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Affiliation(s)
- Katarzyna M Sitnik
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany.
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, 1210, Vienna, Austria.
| | - Fran Krstanović
- Center for Proteomics, Faculty of Medicine, University of Rijeka, 51000, Rijeka, Croatia
| | - Natascha Gödecke
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Ulfert Rand
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Tobias Kubsch
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Henrike Maaß
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Yeonsu Kim
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Ilija Brizić
- Center for Proteomics, Faculty of Medicine, University of Rijeka, 51000, Rijeka, Croatia
| | - Luka Čičin-Šain
- Department of Viral Immunology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany.
- Centre for Individualized Infection Medicine, a joint venture of HZI and MHH, 30625, Hannover, Germany.
- German Centre for Infection Research (DZIF), Hannover-Braunschweig site, 38124, Braunschweig, Germany.
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Gödecke N, Herrmann S, Weichelt V, Wirth D. A Ubiquitous Chromatin Opening Element and DNA Demethylation Facilitate Doxycycline-Controlled Expression during Differentiation and in Transgenic Mice. ACS Synth Biol 2023; 12:482-491. [PMID: 36755406 PMCID: PMC9942253 DOI: 10.1021/acssynbio.2c00450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Synthetic expression cassettes provide the ability to control transgene expression in experimental animal models through external triggers, enabling the study of gene function and the modulation of endogenous regulatory networks in vivo. The performance of synthetic expression cassettes in transgenic animals critically depends on the regulatory properties of the respective chromosomal integration sites, which are affected by the remodeling of the chromatin structure during development. The epigenetic status may affect the transcriptional activity of the synthetic cassettes and even lead to transcriptional silencing, depending on the chromosomal sites and the tissue. In this study, we investigated the influence of the ubiquitous chromosome opening element (UCOE) HNRPA2B1-CBX3 and its subfragments A2UCOE and CBX3 on doxycycline-controlled expression modules within the chromosomal Rosa26 locus. While HNRPA2B1-CBX3 and A2UCOE reduced the expression of the synthetic cassettes in mouse embryonic stem cells, CBX3 stabilized the expression and facilitated doxycycline-controlled expression after in vitro differentiation. In transgenic mice, the CBX3 element protected the cassettes from overt silencing although the expression was moderate and only partially controlled by doxycycline. We demonstrate that CBX3-flanked synthetic cassettes can be activated by decitabine-mediated blockade of DNA methylation or by specific recruitment of the catalytic demethylation domain of the ten-eleven translocation protein TET1 to the synthetic promoter. This suggests that CBX3 renders the synthetic cassettes permissive for subsequent epigenetic activation, thereby supporting doxycycline-controlled expression. Together, this study reveals a strategy for overcoming epigenetic constraints of synthetic expression cassettes, facilitating externally controlled transgene expression in mice.
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Affiliation(s)
- Natascha Gödecke
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Sabrina Herrmann
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Viola Weichelt
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Dagmar Wirth
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany,Institute
of Experimental Hematology, Medical University
Hannover (MHH), 30625 Hannover, Germany,
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Gödecke N, Herrmann S, Hauser H, Mayer-Bartschmid A, Trautwein M, Wirth D. Rational Design of Single Copy Expression Cassettes in Defined Chromosomal Sites Overcomes Intraclonal Cell-to-Cell Expression Heterogeneity and Ensures Robust Antibody Production. ACS Synth Biol 2021; 10:145-157. [PMID: 33382574 DOI: 10.1021/acssynbio.0c00519] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The expression of endogenous genes as well as transgenes depends on regulatory elements within and surrounding genes as well as their epigenetic modifications. Members of a cloned cell population often show pronounced cell-to-cell heterogeneity with respect to the expression of a certain gene. To investigate the heterogeneity of recombinant protein expression we targeted cassettes into two preselected chromosomal hot-spots in Chinese hamster ovary (CHO) cells. Depending on the gene of interest and the design of the expression cassette, we found strong expression variability that could be reduced by epigenetic modifiers, but not by site-specific recruitment of the modulator dCas9-VPR. In particular, the implementation of ubiquitous chromatin opening elements (UCOEs) reduced cell-to-cell heterogeneity and concomitantly increased expression. The application of this method to recombinant antibody expression confirmed that rational design of cell lines for production of transgenes with predictable and high titers is a promising approach.
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Affiliation(s)
- Natascha Gödecke
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Sabrina Herrmann
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Hansjörg Hauser
- Staff Unit Scientific Strategy, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | | | | | - Dagmar Wirth
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
- Institute of Experimental Hematology, Medical University Hannover, Hannover 30625, Germany
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5
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Gödecke N, Riedel J, Herrmann S, Behme S, Rand U, Kubsch T, Cicin-Sain L, Hauser H, Köster M, Wirth D. Synthetic rewiring and boosting type I interferon responses for visualization and counteracting viral infections. Nucleic Acids Res 2020; 48:11799-11811. [PMID: 33137201 PMCID: PMC7672444 DOI: 10.1093/nar/gkaa961] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 09/18/2020] [Accepted: 10/30/2020] [Indexed: 11/12/2022] Open
Abstract
Mammalian first line of defense against viruses is accomplished by the interferon (IFN) system. Viruses have evolved numerous mechanisms to reduce the IFN action allowing them to invade the host and/or to establish latency. We generated an IFN responsive intracellular hub by integrating the synthetic transactivator tTA into the chromosomal Mx2 locus for IFN-based activation of tTA dependent expression modules. The additional implementation of a synthetic amplifier module with positive feedback even allowed for monitoring and reacting to infections of viruses that can antagonize the IFN system. Low and transient IFN amounts are sufficient to trigger these amplifier cells. This gives rise to higher and sustained—but optionally de-activatable—expression even when the initial stimulus has faded out. Amplification of the IFN response induced by IFN suppressing viruses is sufficient to protect cells from infection. Together, this interfaced sensor/actuator system provides a toolbox for robust sensing and counteracting viral infections.
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Affiliation(s)
- Natascha Gödecke
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Jan Riedel
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Sabrina Herrmann
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Sara Behme
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Ulfert Rand
- Department of Vaccinology and Applied Microbiology, Braunschweig 38124, Germany
| | - Tobias Kubsch
- Department of Vaccinology and Applied Microbiology, Braunschweig 38124, Germany
| | - Luka Cicin-Sain
- Department of Vaccinology and Applied Microbiology, Braunschweig 38124, Germany.,Centre for Individualised Infection Medicine (CiiM), a joint venture of Helmholtz Centre for Infection Research and Hannover Medical School, Hannover 30625, Germany
| | - Hansjörg Hauser
- Staff Unit Scientific Strategy, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Mario Köster
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Dagmar Wirth
- RG Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.,Institute of Experimental Hematology, Medical University Hannover, Hannover 30625, Germany
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Gödecke N, Zha L, Spencer S, Behme S, Riemer P, Rehli M, Hauser H, Wirth D. Controlled re-activation of epigenetically silenced Tet promoter-driven transgene expression by targeted demethylation. Nucleic Acids Res 2017; 45:e147. [PMID: 28934472 PMCID: PMC5766184 DOI: 10.1093/nar/gkx601] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 07/03/2017] [Indexed: 12/20/2022] Open
Abstract
Faithful expression of transgenes in cell cultures and mice is often challenged by locus dependent epigenetic silencing. We investigated silencing of Tet-controlled expression cassettes within the mouse ROSA26 locus. We observed pronounced DNA methylation of the Tet promoter concomitant with loss of expression in mES cells as well as in differentiated cells and transgenic animals. Strikingly, the ROSA26 promoter remains active and methylation free indicating that this silencing mechanism specifically affects the transgene, but does not spread to the host's chromosomal neighborhood. To reactivate Tet cassettes a synthetic fusion protein was constructed and expressed in silenced cells. This protein includes the enzymatic domains of ten eleven translocation methylcytosine dioxygenase 1 (TET-1) as well as the Tet repressor DNA binding domain. Expression of the synthetic fusion protein and Doxycycline treatment allowed targeted demethylation of the Tet promoter in the ROSA26 locus and in another genomic site, rescuing transgene expression in cells and transgenic mice. Thus, inducible, reversible and site-specific epigenetic modulation is a promising strategy for reactivation of silenced transgene expression, independent of the integration site.
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Affiliation(s)
- Natascha Gödecke
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany
| | - Lisha Zha
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany
| | - Shawal Spencer
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany
| | - Sara Behme
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany
| | - Pamela Riemer
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany
| | - Michael Rehli
- University Hospital, Dept. Internal Medicine III, Regensburg, Germany
| | - Hansjörg Hauser
- Helmholtz Centre for Infection Research, Dept. of Scientific Strategy, Braunschweig, Germany
| | - Dagmar Wirth
- Helmholtz Centre for Infection Research, RG Model Systems for Infection and Immunity (MSYS), Braunschweig, Germany.,Hannover Medical School, Experimental Hematology, Hannover, Germany
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Kauczok S, Gödecke N, Chichinin AI, Veckenstedt M, Maul C, Gericke KH. Three-dimensional velocity map imaging: setup and resolution improvement compared to three-dimensional ion imaging. Rev Sci Instrum 2009; 80:083301. [PMID: 19725645 DOI: 10.1063/1.3186734] [Citation(s) in RCA: 10] [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] [Indexed: 05/28/2023]
Abstract
For many years the three-dimensional (3D) ion imaging technique has not benefited from the introduction of ion optics into the field of imaging in molecular dynamics. Thus, a lower resolution of kinetic energy as in comparable techniques making use of inhomogeneous electric fields was inevitable. This was basically due to the fact that a homogeneous electric field was needed in order to obtain the velocity component in the direction of the time of flight spectrometer axis. In our approach we superimpose an Einzel lens field with the homogeneous field. We use a simulation based technique to account for the distortion of the ion cloud caused by the inhomogeneous field. In order to demonstrate the gain in kinetic energy resolution compared to conventional 3D Ion Imaging, we use the spatial distribution of H(+) ions emerging from the photodissociation of HCl following the two photon excitation to the V (1)Sigma(+) state. So far a figure of merit of approximately four has been achieved, which means in absolute numbers Delta v/v = 0.022 compared to 0.086 at v approximately = 17,000 m/s. However, this is not a theoretical limit of the technique, but due to our rather short TOF spectrometer (15 cm). The photodissociation of HBr near 243 nm has been used to recognize and eliminate systematic deviations between the simulation and the experimentally observed distribution. The technique has also proven to be essential for the precise measurement of translationally cold distributions.
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Affiliation(s)
- S Kauczok
- Institut für Physikalische und Theoretische Chemie, TU Braunschweig, 38106 Braunschweig, Germany
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Chichinin AI, Shternin PS, Gödecke N, Kauczok S, Maul C, Vasyutinskii OS, Gericke KH. Intermediate state polarization in multiphoton ionization of HCl. J Chem Phys 2006; 125:34310. [PMID: 16863353 DOI: 10.1063/1.2218336] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [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 paper presents the detailed theoretical description of the intermediate state polarization and photofragment angular distribution in resonance enhanced multiphoton ionization (REMPI) of molecules and the experimental investigation of these effects in the E(1)Sigma(+) and V(1)Sigma(+) states of HCl populated by two-photon transitions. It is shown that the intermediate state polarization can be characterized by the universal parameter b which is in general a complex number containing information about the symmetry of the two-photon excitation and possible phase shifts. The photofragment angular distribution produced by one- or multiphoton excitation of the polarized intermediate state is presented as a product of the intermediate state axis spatial distribution and the angular distribution of the photofragments from an unpolarized intermediate state. Experiments have been carried out by two complementary methods: REMPI absorption spectroscopy of rotationally resolved (E,v'=0<--X,v"=0) and (V,v'=12<--X,v"=0) transitions and REMPI via the Q(0) and Q(1) rotational transitions followed by three-dimensional ion imaging detection. The values of the parameter b determined from experiment manifest the mostly perpendicular nature of the initial two-photon transition. The experimentally obtained H(+) -ion fragment angular distributions produced via the Q(1) rotational transition show good agreement with theoretical prediction.
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Affiliation(s)
- A I Chichinin
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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