Understanding communication between patients and healthcare professionals regarding comprehensive biomarker testing in precision oncology: A scoping review

BACKGROUND

Precision oncology, using comprehensive biomarker testing (cBT) to inform individual cancer diagnosis, prognosis and treatment, includes increasingly complex technology and clinical data sets. People impacted by cancer (patients and caregivers) and healthcare professionals (HCPs) face distinct challenges in navigating the cBT and personalized treatment landscape. This review summarizes evidence regarding cBT-related communication between people impacted by cancer and HCPs and identifies important avenues for future research in precision oncology.

METHODS

A scoping review was conducted using records published in PubMed during January 2017-August 2022, focusing on the breadth of topics on patient-HCP communication and knowledge resources used by HCPs as guidance in cBT-related communication. Data were extracted from records meeting inclusion criteria, and findings were summarized according to main topics.

RESULTS

The search identified 287 unique records and data were extracted from 42 records, including nine from expert input. Most records originated from the United States included patients with different types of cancer, and oncologists were the main HCPs. Patients' motivation for undergoing cBT and receiving results was generally high in different settings. However, patients' understanding of cBT-related concepts was limited, and their knowledge and information preferences changed based on cBT implications and significance to family members. HCPs were valued by patients as a trusted source of information. Limited evidence was available on HCPs' information-seeking behavior and factors influencing cBT-related knowledge and confidence, often self-reported as insufficient.

CONCLUSIONS

Patient education by knowledgeable and confident HCPs, information management and a caring patient-HCP relationship communicating continuity of care regardless of cBT results are crucial to empower patients and shared decision-making in precision oncology. More data on the process and structure of cBT-related communication, distinction between and characterization of different timepoints of patient-HCP interactions are needed.

Stressors related to the COVID-19 pandemic and their association with distress, depressive, and anxiety symptoms in cancer out-patients

Patients with cancer might be particularly prone to stress caused by the COVID-19 pandemic. The aim of this study was to investigate the impact of pandemic-related stressors on oncological patients' psychological well-being. During the second wave of the COVID-19 pandemic in Germany 122 cancer out-patients of the Comprehensive Cancer Center Munich reported on COVID-19-related stressors (information satisfaction, threat perception, and fear of disease deterioration) and answered standardized questionnaires for psychosocial distress (DT) as well as depression and anxiety symptoms (PHQ-2, GAD-2). Multiple linear regression analyses were used to identify associations of the COVID-19-related stressors with psychological symptoms, controlling for sociodemographic, psychological (self-efficacy, ASKU) and clinical (somatic symptom burden, SSS-8) variables. Initially, satisfaction with information was significantly negatively associated with all three outcome variables. Fear of disease deterioration was associated with distress and depressive symptoms. After controlling for additional variables, only satisfaction with information remained an independent determinant of anxiety (β = -0.35, p < 0.001). All three outcomes were most strongly determined by somatic symptom burden (β ≥ 0.40, p < 0.001). The results of this study tentatively suggest that physical well-being overrides the relevance of some COVID-19-related stressors for oncological patients' psychological wellbeing. Physical symptoms are strongly tied to personal wellbeing as they are associated with suffering from cancer, which might be more central to personal wellbeing than the possibility of getting infected with SARS-CoV-2. However, satisfaction with the information received seems to be important beyond physical wellbeing, as this emerged as an independent determinant of anxiety.

Driving fitness in clinically stable outpatients with chronic schizophrenia

INTRODUCTION

Driving motorized vehicles is an integral part of individual mobility and a key parameter for employment and social integration. This naturalistic, cross-sectional study investigated the associations between driving fitness, residual symptomatology, olanzapine equivalent, and extrapyramidal symptoms (EPS) in long term stable outpatients with schizophrenia.

METHODS

Beside sociodemographic data, and driving habits, residual symptoms, and EPS were assessed using the Positive and Negative Syndrome Scale (PANSS), and the Modified Simpson Angus Scale (MSAS). PANSS symptoms were analyzed using the Wallwork/Fortgang five-factor model. MSAS cut-off scores ≥3 were defined as positive for EPS. Driving skills were assessed using the Vienna Test System and an expert evaluation.

RESULTS

50 patients were included into the study. Mean PANSS total scores indicated mild residual symptomatology and EPS were not present in 48% of study participants. 44% passed the driving fitness assessment and were considered as competent to drive, 20% were judged to be partially competent and 36% to be incompetent to drive. With the exception of disorganization (r = -0·287, p = 0·048) residual symptoms of schizophrenia did not correlate with driving fitness. However, moderate negative correlations were detected between driving fitness and the severity of EPS (r = -0·554, p = 0·000), age (r = -0·413, p = 0·003) as well as olanzapine equivalent doses (r = -0·432, p = 0·002). These results were not corrected for multiple comparison.

DISCUSSION

The present findings indicate that up to two thirds of clinically stable outpatients with chronic schizophrenia may be (partially) competent to drive. Both the presence of EPS as well as the dosage of antipsychotic medication seem to be of particular relevance in this regard.

[The views of cancer out-patients on the impact of the COVID-19 pandemic]

Hintergrund  Diese Studie untersucht aktuelle Bedürfnisse und Belastungen von ambulanten Krebspatienten im Rahmen der COVID-19-Pandemie.

Material und Methoden  Zwischen 11/2020 und 02/2021 wurden 122 ambulante Krebspatientinnen und -patienten des Comprehensive Cancer Center München in die Studie eingeschlossen und anhand eines standardisierten, halbstrukturierten Interviews zu Wissensstand und Informationsbedürfnissen in Bezug auf COVID-19, Risikowahrnehmung und Sorgen hinsichtlich der ambulanten Krebsbehandlung, COVID-19-spezifischen Belastungen sowie zum Vertrauen in das Gesundheitssystem und der Impfbereitschaft befragt. Zusätzlich wurde psychosozialer Distress anhand des Distress-Thermometers (DT) erhoben.

Ergebnisse  Über ein Drittel der Krebspatienten (34,2 %, n = 41/120) hatte noch Informationsbedarf hinsichtlich der Auswirkungen des Coronavirus auf ihre Erkrankung oder Behandlung. 17,2 % (n = 21/122) waren von Veränderungen der laufenden oder geplanten Krebstherapie betroffen. Bei n = 42/121 (34,7 %) der Patienten zeigte sich ein erhöhter psychosozialer Distress (DT ≥ 5). Die häufigste Corona-spezifische Belastung war die Angst vor einer Überlastung des Gesundheitssystems (77,9 %, n = 95/122), gefolgt von der Befürchtung, dass sich Angehörige noch größere Sorgen um die betroffenen Patienten machen (56,2 %, n = 68/121). 71,2 % (n = 74/104) der Patienten sind bereit, sich impfen zu lassen; 60 % (n = 18/30) der zum Zeitpunkt der Untersuchung Unentschlossenen oder Ablehner wünschen sich vor einer endgültigen Entscheidung für die Impfung ein Informationsgespräch mit ihrem Onkologen/ihrer Onkologin.

Schlussfolgerung  Corona-spezifische Belastungen von Krebspatienten betreffen insbesondere den Verlauf der Therapie, aber auch eine mögliche Überlastung des Gesundheitssystems. Onkologische Behandler-Teams sollten Fragen ihrer Patienten Raum geben, mögliche Unsicherheiten anerkennen, emotionale Unterstützung leisten und auf valide Informationsquellen aufmerksam machen.

Distress in hospitalized cancer patients: Associations with personality traits, clinical and psychosocial characteristics

OBJECTIVE

To improve allocation of psychosocial care and to provide patient-oriented support offers, identification of determinants of elevated distress is needed. So far, there is a lack of evidence investigating the interplay between individual disposition and current clinical and psychosocial determinants of distress in the inpatient setting.

METHODS

In this cross-sectional study, we investigated 879 inpatients with different cancer sites treated in a German Comprehensive Cancer Center. Assessment of determinants of elevated distress included sociodemographic, clinical and psychosocial characteristics as well as dimensions of personality. Multiple linear regression was applied to identify determinants of psychosocial distress.

RESULTS

Mean age of the patients was M = 61.9 (SD = 11.8), 48.1% were women. In the multiple linear regression model younger age (β = -0.061, p = 0.033), higher neuroticism (β = 0.178, p = <0.001), having metastases (β = 0.091, p = 0.002), being in a worse physical condition (β = 0.380, p = <0.001), depressive symptoms (β = 0.270, p = <0.001), not feeling well informed about psychological support (β = 0.054, p = 0.046) and previous uptake of psychological treatment (β = 0.067, p = 0.020) showed significant associations with higher psychosocial distress. The adjusted R² of the overall model was 0.464.

CONCLUSION

Controlling for sociodemographic characteristics and dispositional vulnerability, that is neuroticism, current clinical and psychosocial characteristics were still associated with hospitalized patients' psychosocial distress. Psycho-oncologists should address both, the more transient emotional responses, such as depressive symptoms, as well as more enduring patient characteristics, like neuroticism.

Primary Chemotherapy in a 47-Year-Old Patient with Giant Ulcerative and Necrotizing Nonseminomatous Testicular Germ Cell Tumor

Testicular cancer is a rare disease; however, cure rates are high for all tumor stages. Mostly, the disease is diagnosed in an early (local) stage. We report the case of a 47-year-old male patient with a giant nonseminomatous germ cell tumor. At the time of diagnosis, the patient demonstrated a necrotizing and ulcerating growing mass in the left scrotum with an approximate size of 22 × 18 cm. According to the prognostic classification of the International Germ Cell Cancer Collaborative Group (IGCCCG 1997), the patient exhibited a high-risk profile due to alpha-fetoprotein >10,000 ng/mL and lactate dehydrogenase >10× the upper limit of normal in serum. Primary orchiectomy was infeasible due to the tumor's size, the patient's poor general condition and initial intensive care unit treatment. Primary systemic chemotherapy was applied. After 3 cycles of cisplatin, etoposide and bleomycin, along with 1 cycle of cisplatin, etoposide and ifosfamide, tumor resection with histomorphological examination showed a complete pathological response. Despite the delayed initiation of the therapy, primary chemotherapy was completed timely and showed promising results. Reasons for the late hospitalization were personal responsibilities regarding his family. Better awareness and knowledge of testicular cancer among young men might prevent the here reported delay of medical consultation and avoid testicular tumors of such enormous size. Psychosocial assessment and distress management is important as an integral part of comprehensive care of testicular cancer patients.

Incidence of Quantum Confinement on Dark Triplet Excitons in Carbon Nanotubes

The photophysics of single-wall carbon nanotubes (SWCNTs) is intensively studied due to their potential application in light harvesting and optoelectronics. Excited states of SWCNTs form strongly bound electron-hole pairs, excitons, of which only singlet excitons participate in application relevant optical transitions. Long-living spin-triplet states hinder applications, but they emerge as candidates for quantum information storage. Therefore, knowledge of the triplet exciton energy structure, in particular in a SWCNT chirality dependent manner, is greatly desired. We report the observation of light emission from triplet state recombination, i.e., phosphorescence, for several SWCNT chiralities using a purpose-built spectrometer. This yields the singlet-triplet gap as a function of the SWCNT diameter, and it follows predictions based on quantum confinement effects. Saturation under high microwave power (up to 10 W) irradiation allows the spin-relaxation time for triplet states to be determined. Our study sensitively discriminates whether the lowest optically active state is populated from an excited state on the same nanotube or through Förster exciton energy transfer from a neighboring nanotube.

Information, communication, and cancer patients' trust in the physician: what challenges do we have to face in an era of precision cancer medicine?

Purpose

Despite promising achievements in precision cancer medicine (PCM), participating patients are still faced with manifold uncertainties, especially regarding a potential treatment benefit of molecular diagnostics (MD). Hence, MD poses considerable challenges for patient information and communication. To meet these challenges, healthcare professionals need to gain deeper insight into patients’ subjective experiences. Therefore, this qualitative study examined information aspects of MD programs in cancer patients.

Methods

In two German Comprehensive Cancer Centers, 30 cancer patients undergoing MD participated in semi-structured interviews on information transfer and information needs regarding MD. Additionally, patients provided sociodemographic and medical data and indicated their subjective level of information (visual analogue scale, VAS, 0–10).

Results

On average patients had high levels of information (mean = 7, median = 8); nevertheless 20% (n = 6) showed an information level below 5 points. Qualitative analysis revealed that patients show limited understanding of the complex background of MD and have uncertainties regarding their personal benefit. Further, patients described unmet information needs. Existential threat in awaiting the results was experienced as burdensome. To withstand the strains of their situation, patients emphasized the importance of trusting their physician.

Conclusion

The challenges in PCM consist in providing unambiguous information, especially concerning treatment benefit, and providing guidance and support. Therefore, psycho-oncology needs to develop guidelines for adequate patient communication in order to help healthcare providers and cancer patients to handle these challenges in the developing field of PCM.

Electronic supplementary material

The online version of this article (10.1007/s00520-020-05692-7) contains supplementary material, which is available to authorized users.

Ultralong Spin Lifetime in Light Alkali Atom Doped Graphene

Today's great challenges of energy and informational technologies are addressed with a singular compound, Li- and Na-doped few-layer graphene. All that is impossible for graphite (homogeneous and high-level Na doping) and unstable for single-layer graphene works very well for this structure. The transformation of the Raman G line to a Fano line shape and the emergence of strong, metallic-like electron spin resonance (ESR) modes attest the high level of graphene doping in liquid ammonia for both kinds of alkali atoms. The spin-relaxation time in our materials, deduced from the ESR line width, is 6-8 ns, which is comparable to the longest values found in spin-transport experiments on ultrahigh-mobility graphene flakes. This could qualify our material as a promising candidate in spintronics devices. On the other hand, the successful sodium doping, this being a highly abundant metal, could be an encouraging alternative to lithium batteries.

Distress in cancer patients: Who are the main groups at risk?

OBJECTIVES

Psychosocial distress is common in cancer patients and survivors and encompasses a broad range of concerns and psychological symptoms. The aim of the current study was to identify subgroups of respondents who experience a specific constellation of distress symptoms.

METHODS

This study uses data from a large data base (n = 21 680) of cancer patients from diverse settings who provided data in the Questionnaire on Distress in Cancer Patients-Short Form (QSC-R10). Cluster analysis was applied to identify subgroups with a distinct constellation of distress symptoms.

RESULTS

The results showed five distinct clusters: minimally distressed patients (46.6% of the sample), highly distressed patients (12.7%), mainly physically distressed patients (15.2%), mainly psychologically distressed patients (15.6%), and mainly socially distressed patients (9.9%). These groups differed with regard to age, sex, cancer site, treatment setting, and disease progression.

CONCLUSION

The results revealed large heterogeneity in the experience of distress. Distress clusters were associated with socio-demographic and clinical variables. These associations might aid a clinician to tailor interventions and to address specific types of distress.

Factors associated with the decline of psychological support in hospitalized patients with cancer

OBJECTIVE

Many distressed cancer patients do not want or, finally, do not use psychological support. This study aimed at identifying factors associated with the decline of psychological support during hospital stay.

METHODS

This cross-sectional study included inpatients with different cancer diagnoses. Distress was assessed using the short form of the Questionnaire on Stress in Cancer Patients-Revised (QSC-R10) and the Distress Thermometer (DT). Multivariable logistic regression was used to identify factors associated with decline.

RESULTS

Of 925 patients, 71.6% (n = 662) declined psychological support. Male sex (OR = 2.54, 95% CI = 1.69-3.80), low psychosocial distress (OR = 3.76, CI = 2.50-5.67), not feeling depressed (OR = 1.93, CI = 1.24-2.99), perceived overload (OR = 3.37, CI = 2.19-5.20), no previous psychological treatment (OR = 1.88, CI = 1.25-2.83), and feeling well informed about psychological support (OR = 1.66, CI = 1.11-2.46) were associated with decline. Among the patients who indicated clinical distress (46.2%), 53.9% declined psychological support. Male sex (OR = 2.96, CI = 1.71-5.12), not feeling depressed (OR = 1.87, CI = 1.12-3.14), perceived overload (OR = 5.37, CI = 3.07-9.37), agreeableness (OR = 0.70, CI = 0.51-0.95), and feeling well informed about psychological support (OR = 1.81, CI = 1.07-3.07) were uniquely associated with decline in this subgroup.

CONCLUSIONS

Decline of psychological support is primarily due to psychological factors. Feeling well informed about support emerged as a relevant factor associated with decline. Thus, design of informational material and education about available psychological services seem crucial.

Psychosocial Distress in Follow-up Care - Results of a Tablet-based Routine Screening in 202 Patients With Sarcoma

BACKGROUND

Patients with sarcoma are particularly vulnerable to psychosocial distress. The aim of this study was to collect preliminary data on the prevalence of psychosocial distress in such patients during follow-up care and identify risk factors associated with higher psycho-oncological stress levels.

PATIENTS AND METHODS

The study retrospectively enrolled 202 patients with bone or soft-tissue sarcomas who underwent routine psychosocial distress screening during their follow-up care. All patients were screened using an electronic cancer-specific questionnaire.

RESULTS

Females and patients who underwent radiotherapy were more distressed. Psychosocial distress levels were markedly higher in the early postoperative phase, but approximately one-third of patients showed high psychosocial distress levels even more than 2 years postoperatively.

CONCLUSION

The results underscore the importance of routine psychosocial distress screenings in patients with sarcoma, which should be performed throughout the follow-up period.

Suitability of the shallow water hydrothermal system at Ambitle Island (Papua New Guinea) to study the effect of high pCO2 on coral reefs

Volcanic CO₂ seeps were successfully used to predict coral reef response to ocean acidification, although toxic elements, often characteristic of hydrothermal vents were rarely reported. We measured the physicochemical conditions, seawater carbonate chemistry and trace elements in Tutum Bay, Papua New Guinea. There, intense emission of hydrothermal fluids and CO₂ expose the coral reef to a seawater pH_T between 7.6 and 7.7. Arsenic and silica were enriched by up to six times in surface seawater, while bottom concentrations were lower and thus similar to coral reefs worldwide. Manganese, cesium, iron and zinc concentrations fell into the range of other coastal environments. Our measurements suggest that Tutum Bay is a suitable site to study the response of coral reefs to high pCO₂. Considering that arsenic is a common metal in hydrothermal fluids, its characterization should be included in any study that uses volcanic CO₂ seeps as natural laboratories for ocean acidification.

An optically detected magnetic resonance spectrometer with tunable laser excitation and wavelength resolved infrared detection

We present the development and performance of an optically detected magnetic resonance (ODMR) spectrometer. The spectrometer represents advances over similar instruments in three areas: (i) the exciting light is a tunable laser source which covers much of the visible light range, (ii) the optical signal is analyzed with a spectrograph, (iii) the emitted light is detected in the near-infrared domain. The need to perform ODMR experiments on single-walled carbon nanotubes motivated the present development and we demonstrate the utility of the spectrometer on this material. The performance of the spectrometer is critically compared to similar instruments. The present development opens the way to perform ODMR studies on various new materials such as molecules and luminescent quantum dots where the emission is in the near-infrared range and requires a well-defined excitation wavelength and analysis of the scattered light.

Atomically precise semiconductor--graphene and hBN interfaces by Ge intercalation

The full exploration of the potential, which graphene offers to nanoelectronics requires its integration into semiconductor technology. So far the real-world applications are limited by the ability to concomitantly achieve large single-crystalline domains on dielectrics and semiconductors and to tailor the interfaces between them. Here we show a new direct bottom-up method for the fabrication of high-quality atomically precise interfaces between 2D materials, like graphene and hexagonal boron nitride (hBN), and classical semiconductor via Ge intercalation. Using angle-resolved photoemission spectroscopy and complementary DFT modelling we observed for the first time that epitaxially grown graphene with the Ge monolayer underneath demonstrates Dirac Fermions unaffected by the substrate as well as an unperturbed electronic band structure of hBN. This approach provides the intrinsic relativistic 2D electron gas towards integration in semiconductor technology. Hence, these new interfaces are a promising path for the integration of graphene and hBN into state-of-the-art semiconductor technology.

Energy sources for chemolithotrophs in an arsenic- and iron-rich shallow-sea hydrothermal system

The hydrothermally influenced sediments of Tutum Bay, Ambitle Island, Papua New Guinea, are ideal for investigating the chemolithotrophic activities of micro-organisms involved in arsenic cycling because hydrothermal vents there expel fluids with arsenite (As(III)) concentrations as high as 950 μg L(-1) . These hot (99 °C), slightly acidic (pH ~6), chemically reduced, shallow-sea vent fluids mix with colder, oxidized seawater to create steep gradients in temperature, pH, and concentrations of As, N, Fe, and S redox species. Near the vents, iron oxyhydroxides precipitate with up to 6.2 wt% arsenate (As(V)). Here, chemical analyses of sediment porewaters from 10 sites along a 300-m transect were combined with standard Gibbs energies to evaluate the energy yields (-ΔG(r)) from 19 potential chemolithotrophic metabolisms, including As(V) reduction, As(III) oxidation, Fe(III) reduction, and Fe(II) oxidation reactions. The 19 reactions yielded 2-94 kJ mol(-1) e(-) , with aerobic oxidation of sulphide and arsenite the two most exergonic reactions. Although anaerobic As(V) reduction and Fe(III) reduction were among the least exergonic reactions investigated, they are still potential net metabolisms. Gibbs energies of the arsenic redox reactions generally correlate linearly with pH, increasing with increasing pH for As(III) oxidation and decreasing with increasing pH for As(V) reduction. The calculated exergonic energy yields suggest that micro-organisms could exploit diverse energy sources in Tutum Bay, and examples of micro-organisms known to use these chemolithotrophic metabolic strategies are discussed. Energy modeling of redox reactions can help target sampling sites for future microbial collection and cultivation studies.

[Radiation protection clothing in X-ray diagnostics - comparison of attenuation equivalents in narrow beam and inverse broad-beam geometry]

PURPOSE

Standard DIN EN 61 331-1 for attenuation measurements in the narrow and broad beam as well as DIN 6857-1 for the determination of shielding properties in the inverse broad-beam geometry are available for testing the attenuation of protection clothing. The attenuation measurements in the narrow beam don't consider scattered radiation and fluorescence due to the arrangement. This leads to the fact that the protective effect of lead-free materials will be misestimated when compared to lead. Therefore, the differences in attenuation equivalents, determined by both test methods for topical radiation protection aprons, were examined.

MATERIALS AND METHODS

The attenuations in inverse broad-beam geometry according to DIN 6857-1 and in the narrow beam according to DIN EN 61 331-1 were measured using commercially available aprons. They were made of lead, lead-reduced and lead-free materials. For determination of the attenuation equivalents, certificated lead-foils with high purity and a precise thickness of 0.1 to 1.25 mm were used.

RESULTS

The measurements in the narrow beam according to DIN EN 61 331-1 showed that nearly all aprons reach the required lead equivalent at mid-range tube voltages of 100 kV. At higher and lower tube voltages, the requirements of DIN EN 61 331-3 were largely not met. In contrast, the testing of the same aprons in inverse broad-beam geometry according to DIN 6857-1 showed that only a few aprons meet the requirements for being classified in the nominal protection class.

CONCLUSION

The measurements suggest that testing method DIN 6857-1 has yet to prevail and that manufacturers are just beginning to develop the appropriate protective materials.

Tunable band gap in hydrogenated quasi-free-standing graphene

We show by angle-resolved photoemission spectroscopy that a tunable gap in quasi-free-standing monolayer graphene on Au can be induced by hydrogenation. The size of the gap can be controlled via hydrogen loading and reaches approximately 1.0 eV for a hydrogen coverage of 8%. The local rehybridization from sp(2) to sp(3) in the chemical bonding is observed by X-ray photoelectron spectroscopy and X-ray absorption and allows for a determination of the amount of chemisorbed hydrogen. The hydrogen induced gap formation is completely reversible by annealing without damaging the graphene. Calculations of the hydrogen loading dependent core level binding energies and the spectral function of graphene are in excellent agreement with photoemission experiments. Hydrogenation of graphene gives access to tunable electronic and optical properties and thereby provides a model system to study hydrogen storage in carbon materials.

Spectroscopic characterization of N-doped single-walled carbon nanotube strands: an X-ray photoelectron spectroscopy and Raman study

We have studied in detail the carbon and nitrogen bonding environments in nitrogen-doped single-walled carbon nanotubes (SWCNTs). The samples consisting of long strands of N-doped SWCNTs were synthesized using an aerosol assisted chemical vapor deposition method involving benzylamine-ethanol-ferrocene solutions. The studied samples were produced using different benzylamine concentrations in the solutions, and exhibited a maximum concentration of ca. 0.3%at of N, determined by X-ray photoelectron spectroscopy (XPS). In general, we observed that the ratio between substitutional nitrogen and the pyridine-like bonded nitrogen varied upon the precursor composition. Moreover, we have observed that the sp2-like substitutional configuration of the C-N bond does not exceed the 50% of the total N atomic incorporation. In addition, we have characterized all these samples using Raman spectroscopy and electron microscopy.

Screening the missing electron: nanochemistry in action

The excitement of nano-test-tube chemistry in a single-walled carbon nanotube is exemplified in our study on electron doping in carbon nanotubes. Electron doping through the 1D van Hove singularity of single-walled carbon nanotubes is realized via a chemical reaction of an encapsulated organocerium compound, CeCp3. The decomposition of CeCp3 inside the carbon nanotubes increases the doping level and greatly enhances the density of conduction electrons. The transition of the cerium encapsulating semiconducting tubes to metallic results in enhanced screening of the photoexcited core hole potential. This fact illustrates the importance of many body effects in understanding core-level excitation process in carbon nanotubes.

Single-walled carbon nanotubes synthesis: a direct comparison of laser ablation and carbon arc routes

Carbon arc and chemical vapor deposition are at present the most efficient methods for mass production of single-walled carbon nanotubes. However, laser ablation is renowned for high quality nanotubes with narrow diameter distributions and hence is also of great interest. The aim of this work was to compare both the carbon arc and laser ablation techniques with respect to the quality--and relative yield of the produced SWCNTs. For this comparative study we used Fe as the catalyst, which is known not to be very active in laser ablation. However, we show this is not the case when H2 is included in the reaction. The reactions for both synthesis routes were carried out in a N2-H2 (95-5% vol.) atmosphere. The same homogenous carbon rods with different iron contents, between 1 and 5 at.% were used as the carbon feedstock and catalyst supply in both synthesis routes. Additionally, two types of carbon rods containing 1 at.% Fe with different graphitization degrees were also investigated. In the arc-discharge case, the low-graphitized electrode produced a web-like product rich in SWCNTs, while the high-graphitized carbon rods yielded soot containing carbon-encapsulated iron nanocrystallites, amorphous carbon nanoparticles, and surprisingly a small fraction of SWCNTs. With laser ablation synthesis, the Fe content and the reactor temperature significantly influenced the SWCNTs yield. Carbon arc plasma diagnostics were also performed. By using optical emission and Absorption spectroscopy the plasma temperature, C2 and CN radical content in the arc zone were determined.

Linear plasmon dispersion in single-wall carbon nanotubes and the collective excitation spectrum of graphene

We have measured a strictly linear pi plasmon dispersion along the axis of individualized single-wall carbon nanotubes, which is completely different from plasmon dispersions of graphite or bundled single-wall carbon nanotubes. Comparative ab initio studies on graphene-based systems allow us to reproduce the different dispersions. This suggests that individualized nanotubes provide viable experimental access to collective electronic excitations of graphene, and it validates the use of graphene to understand electronic excitations of carbon nanotubes. In particular, the calculations reveal that local field effects cause a mixing of electronic transitions, including the "Dirac cone," resulting in the observed linear dispersion.

Electron-electron correlation in graphite: a combined angle-resolved photoemission and first-principles study

The full three-dimensional dispersion of the pi bands, Fermi velocities, and effective masses are measured with angle-resolved photoemission spectroscopy and compared to first-principles calculations. The band structure by density-functional theory underestimates the slope of the bands and the trigonal warping effect. Including electron-electron correlation on the level of the GW approximation, however, yields remarkable improvement in the vicinity of the Fermi level. This demonstrates the breakdown of the independent electron picture in semimetallic graphite and points toward a pronounced role of electron correlation for the interpretation of transport experiments and double-resonant Raman scattering for a wide range of carbon based materials.

Transition from a Tomonaga-Luttinger liquid to a fermi liquid in potassium-intercalated bundles of single-wall carbon nanotubes

We report on the first direct observation of a transition from a Tomonaga-Luttinger liquid to a Fermi-liquid behavior in potassium-intercalated mats of single-wall carbon nanotubes. Using high resolution photoemission spectroscopy, an analysis of the spectral shape near the Fermi level reveals a Tomonaga-Luttinger liquid power law scaling in the density of states for the pristine sample and for low dopant concentration. As soon as the doping is high enough to achieve a filling of the conduction bands of the semiconducting tubes, a distinct transition to metallic single-wall carbon nanotube bundles with the scaling behavior of a normal Fermi liquid occurs.

Unusual high degree of unperturbed environment in the interior of single-wall carbon nanotubes

Double wall carbon nanotubes were prepared by vacuum annealing of single wall carbon nanotubes filled with C60. Strong evidence is provided for a highly defect free and unperturbed environment in the interior of the tubes. This is concluded from unusual narrow Raman lines for the radial breathing mode of the inner tubes. Lorentzian linewidths scale down to 0.35 cm(-1) which is almost 10 times smaller than linewidths reported so far for this mode. A splitting is observed for the majority of the Raman lines. It is considered to originate from tube-tube interaction between one inner tube and several different outer tubes. The highest RBM frequency detected is 484 cm(-1) corresponding to a tube diameter of only 0.50 nm. Labeling of the Raman lines with the folding vector is provided for all inner tubes. This labeling is supported by density functional calculations.

Infrared response of multiwalled boron nitride nanotubes

We report the infrared (IR) response of bulk samples of multiwalled boron nitride nanotubes, produced by a substitution reaction from single walled carbon nanotubes, which is dominated by two characteristic BN-vibrations at 800 and 1372 cm-1.

Diameter selective charge transfer in p- and n-doped single wall carbon nanotubes synthesized by the HiPCO method

The unusually broad diameter distribution of single wall carbon nanotubes (SWCNTs) in a HiPCO derived sample made it possible to observe for the first time a selective loss of Raman resonances corresponding to large diameter tubes upon both p- (FeCl3) and n-type (K) doping.

Anisotropy and interplane interactions in the dielectric response of graphite

We determined the anisotropic dielectric response of graphite by means of time-dependent density-functional theory and high-resolution valence electron energy-loss spectroscopy. The calculated loss function was in very good agreement with the experiment for a wide range of momentum-transfer orientations with respect to the graphitic basal planes, provided that local-field effects were included in the response. The calculations also showed strong effects of the interlayer Coulomb interaction on the total pi+sigma plasmon. This finding must be taken into account for the explanation of recent loss spectra of carbon nanotube materials.

Metallic polymers of C(60) inside single-walled carbon nanotubes

Doping induced polymerization of C(60) inside single-walled carbon nanotubes is reported using Raman spectroscopy and resistivity measurements as a probe. The resistivity changes from semiconducting for the undoped system to metallic for the doped system. For full intercalation, we observe a chemical reaction inside the nanotubes which leads to a one-dimensional polymeric C(60)(-6) chain which has metallic character. The resonance and the oscillations of the radial breathing mode are lost suggesting an up-shift of the Fermi level to beyond the third Van Hove singularity in the semiconducting tubes. The linewidth of the radial breathing mode now represents directly the Gaussian distribution of tube diameters.

Joys and pitfalls of fermi surface mapping in Bi(2)Sr(2)CaCu(2)O(8+delta) using angle resolved photoemission

On the basis of angle-scanned photoemission data recorded using unpolarized radiation, with high (E,k) resolution, and an extremely dense sampling of k space, we resolve the current controversy regarding the normal state Fermi surface (FS) in Bi(2)Sr(2)CaCu(2)O(8+delta). The true picture is simple, self-consistent, and robust: the FS is holelike, with the form of rounded tubes centered on the corners of the Brillouin zone. Two further types of features are also clearly observed: shadow FSs, which are most likely to be due to short range antiferromagnetic spin correlations, and diffraction replicas of the main FS caused by passage of the photoelectrons through the modulated Bi-O planes.