An experimental setup for spectroscopy applications of optically generated VUV and XUV radiation

In this paper, we present an experimental setup to study photoionization of atoms and molecules using the high-order harmonic radiation generated by a highly non-linear process. We report on the characteristics of this table-top experimental apparatus showing also the results of the photoionization of krypton gas, by the use of the ninth order harmonic of fs Ti : S laser, observed both in the electron spectrum and in the mass spectrum.     

DISCO: a low‐energy multipurpose beamline at synchrotron SOLEIL

DISCO, a novel low‐energy beamline covering the spectrum range from the VUV to the visible, has received its first photons at the French synchrotron SOLEIL. In this article the DISCO design and concept of three experimental stations serving research communities in biology and chemistry are described. Emphasis has been put on high flux generation and preservation of polarization at variable energy resolutions. The three experiments include a completely new approach for microscopy and atmospheric pressure experiments as well as a `classical' synchrotron radiation circular dichroism station. Preliminary tests of the optical design and technical concept have been made. Theoretical predictions of the beam have been compared with the first images produced by the first photons originating from the large‐aperture bending‐magnet source. Results are also reported concerning the cold finger used to absorb hard X‐ray radiation in the central part of the synchrotron beam and to avoid heavy thermal load on the following optics. Wavelength selection using monochromators with different gratings for each experimental set‐up as well as beam propagation and conditioning throughout the optical system are detailed. First photons comply very well with the theoretical calculations.     

燃烧:一个不息的话题--同步辐射单光子电离技术在燃烧研究中的应用

燃烧应用于工业、农业、交通运输、国防等各个领域，提供了当今社会极大部分的能量需求。100多万年前人类就开始利用燃烧，人类研究燃烧已经有150多年的历史。本文介绍了将同步辐射真空紫外单光子电离技术结合分子束取样，应用于燃烧研究中，可以探测到燃烧中的各种中间物，包括稳定的和不稳定的产物。通过扫描光子能量，测量产物的光电离效率谱，可以区分其同分异构体，因此，利用这种新的诊断技术，在150年后的今天，我们仍然可以在火焰中发现很多新的燃烧中间体，为发展燃烧动力学模型提供精确的实验数据。最后，展望该方法在其它学科中的可能应用。     

探测大气污染源的新方法——激光质谱法

此文介绍了大气污染源检测的新方法 -激光质谱法的原理、特点和近几年作者所在课题组在研究大气污染分子方面的成果以及正在开展的应用激光质谱法测汽车、摩托车尾气的工作。     

Quantification routines for adsorption studies in static secondary ion mass spectrometry and the effect of ionisation probability

It is shown that the usual method of quantification of surface composition in static secondary ion mass spectrometry (SSIMS), which is purely comparative in nature, is unsuitable for adsorption studies by SSIMS. This is because of the effect of the ionisation efficiency and ion stability of a particular ion produced from a molecule adsorbed on the surface of a substrate. The established routine results in a non-linear relationship between calculated relative surface coverage and the ion selected to characterise the adsorbate. The application of a new normalisation routine to time-of-flight secondary ion mass spectrometry (ToF-SIMS) data has been used to account for this discrepancy, and also takes into account the effect of a possible contribution from the clean substrate to the ion selected to characterise the adsorbate molecule. This routine is suggested only for use with organic secondary ions, where the ionisation potential of such ions is of a comparable magnitude, and should prove particularly useful in the application of surface analysis techniques to adsorption studies.     

Uranium passivation by C implantation: A photoemission and secondary ion mass spectrometry study

Implantation of 33 keV C⁺ ions into polycrystalline U²³⁸ with a dose of 4.3 × 10¹⁷ cm⁻² produces a physically and chemically modified surface layer that prevents further air oxidation and corrosion. X-ray photoelectron spectroscopy and secondary ion mass spectrometry were used to investigate the surface chemistry and electronic structure of this C⁺ ion implanted polycrystalline uranium and a non-implanted region of the sample, both regions exposed to air for more than a year. In addition, scanning electron microscopy was used to examine and compare the surface morphology of the two regions. The U 4f, O 1s and C 1s core-level and valence band spectra clearly indicate carbide formation in the modified surface layer. The time-of-flight secondary ion mass spectrometry depth profiling results reveal an oxy-carbide surface layer over an approximately 200 nm thick UC layer with little or no residual oxidation at the carbide layer/U metal transitional interface.     

A pilot experiment for mass measurement at CSRe

A pilot experiment of mass measurement was performed at CSRe with the method of isochronous mass spectrometry. The secondary fragments produced via RIBLL2 with the primary beam of 400 MeV/u 36Ar delivered by CSRm were injected into CSRe. The revolution periods of the stored ions, which depend on the mass-to-charge ratios of the stored ions, were measured with a time-of-flight detector system. The results show that the mass resolution around 8×10-6 for Δm/m is achieved.     

Extent of coverage of surfaces treated with hydrophobizing microemulsions: A mass spectrometry and contact angle study

Glass surfaces were treated with various hydrophobizing microemulsions (HME) containing mineral seal oil or polyisobutylene as hydrophobes emulsified by dimethyl dicoco ammonium chloride (i.e. mimicking commercial car wash practices) and characterized by mass spectrometry (MS) and contact angle measurements. The cationic emulsifier mediates the anchoring of hydrophobes to the polar glass surface. It is demonstrated that by the use of even very low (0.3-3.0 w%) HME concentrations the surfaces become hydrophobic and repel water even after numerous (∼20) rinsing cycles. According to MS evidence, however, the surfaces are not fully saturated with hydrophobes and the unprotected areas remain vulnerable to environmental damage.     

A pilot experiment for mass measurement at CSRe

A pilot experiment of mass measurement was performed at CSRe with the method of isochronous mass spectrometry. The secondary fragments produced via RIBLL2 with the primary beam of 400 MeV/u ^36Ar delivered by CSRm were injected into CSRe. The revolution periods of the stored ions,which depend on the mass-to-charge ratios of the stored ions,were measured with a time-of-flight detector system. The results show that the mass resolution around 8×10^-6 for △m/m is achieved.     

129I加速器质谱分析研究

通过对129I加速器质谱(AMS)分析中影响敏度和准确度各种参数的研究,如靶电极制备、压样、靶样中辅助介质（Matrix）的选择及使用比例等,优化了用于3 MV加速器质谱仪的SO-110型离子源的条件参数,确定129I-AMS测量的最佳靶电极材料为Cu,最佳的辅助介质为Nb粉末,Nb与AgI样品的最佳体积比为3∶1。在此条件下可以获得稳定且持续的I-束流进行测量129I/127I原子比值,实验测得西安加速器质谱仪的129I/127I本底值为1.5210-14。     

利用光谱和质谱成像技术实现指纹痕量检测

近年来,依赖于先进光源的化学成像技术迅速发展,极大提高了痕量检测的准确性,在公共安全、环境、食品、医药、考古等领域具有重要的实用价值.在痕量检测中,通过将成像技术与光谱测量技术、质谱技术等相结合,能够同时获取检验对象的物质组成和二维图像信息,不仅可以揭示材料表面的痕量物质成分及其分布,还可以在提高检验灵敏度的情况下,减少甚至避免传统检测手段所需要的特殊显现剂,因此与其他检验方法具有良好的兼容性.本文以指纹检验这一典型的痕量检测问题为例,阐述基于光谱和质谱成像技术的化学成像方法在痕量检测领域中的应用,从定向针对特定组分的化学成像和非定向的直接化学成像两个方面,综述了在指纹显现或显现增强中获得应用的主要成像手段,包括可见-近红外成像、红外成像、拉曼成像、质谱成像等.     

Penning trap mass spectrometry for nuclear structure studies

High-precision mass measurements as performed at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN are an important contribution to the investigation of nuclear structure. Precise nuclear masses with less than 0.1 ppm relative mass uncertainty allow stringent tests of mass models and formulae that are used to predict mass values of nuclides far from the valley of stability. Furthermore, an investigation of nuclear structure effects like shell or sub-shell closures, deformations, and halos is possible. In addition to a sophisticated experimental setup for precise mass measurements, a radioactive ion-beam facility that delivers a large variety of short-lived nuclides with sufficient yield is required. An overview of the results from the mass spectrometer ISOLTRAP is given and its limits and possibilities are described.      

Molecular-beam mass spectrometry study of oxy-combustion in a novel coal-plate experiment

Oxy-fuel coal combustion could play a significant role in the foreseeable future for its application in carbon capture and storage (CSS) technologies. Therefore, detailed knowledge about the ongoing chemical kinetics in the combustion process is necessary. Here, we present an explorative approach to study volatile species gas phase kinetics in a novel coal-plate experiment probed with molecular-beam mass spectrometry. This coupling allows for time-resolved quantitative measurements of the gas-phase directly above the surface of solid fuels, which aid gaining more insight into the gas phase chemistry during coal combustion by detailed speciation information. Two coal samples, a rhenish lignite and a coal manufactured from hydrothermal carbonization, were chosen for this investigation due to their similar classification but different molecular structures. For both samples, our measurements show a two-stage devolatilization phase separated by a char-oxidation phase which can be attributed to the interaction of oxygen consumption in the gas phase and on the surface and the release of volatiles from deeper layers of the plate. Furthermore, detailed speciation data of light, oxygenated, and tar species allowed to identify fuel structure-specific decomposition patterns of the two different coal materials, thus providing comprehensive data that can be used for future model validation purposes.     

Development of an experimental set‐up for low‐temperature spectroscopic studies of matrix‐isolated molecules and molecular ices using synchrotron radiation

An experimental set‐up for studying photophysics and photochemistry of molecules in an inert gas medium (matrix‐isolated) and in the ice phase at low temperatures has been developed and commissioned at the Photophysics beamline, Indus‐1 synchrotron radiation source. This end‐station uses an in‐house‐developed closed‐cycle cryostat for achieving cryo‐temperatures (～10 K). Synchrotron radiation from the Photophysics beamline is used as the source of UV–VUV photons and the system is equipped with a Fourier transform infrared spectrometer for characterization of the molecular species formed at low temperature. Various individual components of the end‐station like closed‐cycle cryostat, experimental chamber, gas mixing and deposition systems are tested to ascertain that the desired performance criteria are satisfied. The performance of the composite system after integration with the Photophysics beamline is evaluated by recording IR and UV–VUV photoabsorption spectra of sulfur dioxide at low temperatures (10 K), both in the ice phase as well as isolated in argon matrices. Results obtained are in good agreement with earlier literature, thus validating the satisfactory performance of the system. As an off‐shoot of the study, the VUV absorption spectrum of matrix‐isolated SO₂ in argon matrix up to 10.2 eV is reported here for the first time. This experimental end‐station will provide new opportunities to study photon‐induced reactions in molecules of environmental, astrochemical and industrial importance. Details of the design, development and initial experimental results obtained are presented.     

Influence of ferrocene addition to a laminar premixed propene flame: Laser diagnostics, mass spectrometry and numerical simulations

The detailed influence of ferrocene in a low-pressure, fuel-rich, laminar, premixed propene/oxygen/argon flat flame was investigated experimentally using molecular beam sampling mass spectrometry (MBMS), laser-induced fluorescence (LIF), and compared to numerical simulations. MBMS was applied to analyze the species profiles of important intermediates in the flames with and without ferrocene doping. The concentration profile of iron atoms was measured with absorption sensitive LIF, which provides absolute number densities without additional calibrations. The flame temperature was obtained by two-line OH LIF measurements. One dimensional numerical simulations of the flames using detailed models from the literature were performed and the modeling results are compared with the experimental measurements. The iron measurements show reasonable agreement with the numerical simulation, while some discrepancies were found at larger heights. The MBMS measurements show a decrease in flame velocity when ferrocene was added, which was not provided by the model.     

DESIRS: a state‐of‐the‐art VUV beamline featuring high resolution and variable polarization for spectroscopy and dichroism at SOLEIL

DESIRS is a new undulator‐based VUV beamline on the 2.75 GeV storage ring SOLEIL (France) optimized for gas‐phase studies of molecular and electronic structures, reactivity and polarization‐dependent photodynamics on model or actual systems encountered in the universe, atmosphere and biosphere. It is equipped with two dedicated endstations: a VUV Fourier‐transform spectrometer (FTS) for ultra‐high‐resolution absorption spectroscopy (resolving power up to 10⁶) and an electron/ion imaging coincidence spectrometer. The photon characteristics necessary to fulfill its scientific mission are: high flux in the 5–40 eV range, high spectral purity, high resolution, and variable and well calibrated polarizations. The photon source is a 10 m‐long pure electromagnetic variable‐polarization undulator producing light from the very near UV up to 40 eV on the fundamental emission with tailored elliptical polarization allowing fully calibrated quasi‐perfect horizontal, vertical and circular polarizations, as measured with an in situ VUV polarimeter with absolute polarization rates close to unity, to be obtained at the sample location. The optical design includes a beam waist allowing the implementation of a gas filter to suppress the undulator high harmonics. This harmonic‐free radiation can be steered toward the FTS for absorption experiments, or go through a highly efficient pre‐focusing optical system, based on a toroidal mirror and a reflective corrector plate similar to a Schmidt plate. The synchrotron radiation then enters a 6.65 m Eagle off‐plane normal‐incidence monochromator equipped with four gratings with different groove densities, from 200 to 4300 lines mm^?1, allowing the flux‐to‐resolution trade‐off to be smoothly adjusted. The measured ultimate instrumental resolving powers are 124000 (174 µeV) around 21 eV and 250000 (54 µeV) around 13 eV, while the typical measured flux is in the 10¹⁰–10¹¹ photons s^?1 range in a 1/50000 bandwidth, and 10¹²–10¹³ photons s^?1 in a 1/1000 bandwidth, which is very satisfactory although slightly below optical simulations. All of these features make DESIRS a state‐of‐the‐art VUV beamline for spectroscopy and dichroism open to a broad scientific community.     

Developing of a fast cryodetector read-out for mass spectrometry

We report on the development of a SQUID read-out for a fast cryogenic detector with superconducting phase transition thermometer. To avoid the usual transformer matching and modulation–demodulation technique we are using a second SQUID to amplify the signal of a first stage input SQUID. A bandwidth of 2 MHz and a slew rate of 2×10⁵ Φ₀ s⁻¹ were achieved. The system is developed for the detection of large protein molecules in a time of flight mass spectrometer.     

Secondary ion mass spectrometry and X-ray photoelectron spectroscopy studies on TiO2 and nitrogen doped TiO2 thin films

Anatase phase TiO₂ and nitrogen (N) doped TiO₂ thin films were synthesized by an ultrasonic spray pyrolysis technique on c-Si (100) substrates in the temperature range 300-550 °C. The former used a precursor solution of titanium oxy acetylacetonate in methanol whereas the later used a titanium oxy acetylacetonate hexamine mixture in methanol. Homogeneity across the film’s thickness and the nature of the film-substrate interface were studied by dynamic depth profiling acquired using secondary ion mass spectrometry SIMS. The stoichiometry and bonding state of various species present in the films were studied using X-ray photoelectron spectroscopy (XPS). N-doping was confirmed by both SIMS and XPS. XPS studies revealed that the nitrogen content of the films synthesized at 300 °C (3.2%) is high compared to that of films made at 350 °C (1.3%).     

A novel method for analyzing formalin-fixed paraffin embedded (FFPE) tissue sections by mass spectrometry imaging

Significant advances have been made in the past decade in the field of mass spectrometry imaging (MS imaging). It is a relatively unestablished technique aimed at direct, high-sensitive and spatially exclusive detection of biological molecules from the surface of tissue sections, so that semi-quantitative distribution map of the analyte can be reconstituted from the mass spectra obtained. There is tremendous potential in its application especially in clinical field, such as biomarker discovery or pharmacokinetic study. However, vast majority of the work has been performed on frozen tissue sections, while it remains generally unpractical to produce frozen sections with clinically resected tumor samples. Here we report our novel sample preparation technique that enabled MS imaging from formalin-fixed paraffin embedded (FFPE) tissue section, including retrospective archive as old as 11 years. FFPE sections were first dewaxed with pre-warmed xylene, and exposed tissue surface was enzymatically digested in nanoliter scale droplets to retain analyte localization. As a result, we succeeded in obtaining MS images of peptide peaks derived from several proteins, identified by MS/MS analysis, using ovarian cancer FFPE sections. The qualities of mass spectra obtained by this method were not significantly different from those obtained from frozen sections. By this, we opened the door to retrospective study of past clinical cases in aim to discover molecular biomarker.     

Three dimensional imaging using secondary ion mass spectrometry and atomic force microscopy

With the breakthroughs in lateral resolution with regards to secondary ion mass spectroscopy in recent years, new areas of research with much promise have opened up to the scientific community. Even though the much improved lateral resolution of 50 nm can effectively deliver more accurate 3D-images, the traditional 3D reconstructions, consisting of compiling previously acquired successive secondary ion mass spectrometry images into a 3D-stack, do not represent the real localized chemical distribution of the sputtered volume. Based on samples initially analyzed on the Cameca NanoSIMS 50 instrument, this paper portrays the advantages of combining the topographical information from atomic force microscopy and the chemical information from secondary ion mass spectrometry. Taking account of the roughness evolution within the analyzed zone, 3D reconstructions become a lot more accurate and allow an easier interpretation of results. On the basis of an Al/Cu sample, a comparison between traditional 3D imaging and corrected 3D reconstructions is given and the advantages of the newly developed 3D imaging method are explained.