Communication: Water activation and splitting by single metal-atom anions.

We report experimental and computational results pertaining to the activation and splitting of single water molecules by single atomic platinum anions. The anion photoelectron spectra of [Pt(HO)], formed under different conditions, exhibit spectral features that are due to the anion-molecule complex, Pt(HO), and to the reaction intermediates, HPtOH and HPtO, in which one and two O-H bonds have been broken, respectively. Additionally, the observations of PtO and H in mass spectra strongly imply that water splitting via the reaction Pt + HO → PtO + H has occurred.

High-Resolution Absorption and Electronic Circular Dichroism Spectra of (R)-(+)-1-Phenylethanol. Confident Interpretation Based on the Synergy between Experiments and Computations.

Using density functional theory and its time-dependent extension for excited states, the S →S high-resolution vibronic absorption and electronic circular dichroism spectra of (R)-(+)-1-phenylethanol are computed and compared to experimental spectra measured in jet-cooled conditions in the region within 1000 cm of the 0-0 transition. The agreement between theory and computation is satisfactory and allows a confident assignment of several experimental bands in terms of fundamentals of different modes. Cases are documented for which the analysis of optical anisotropy factors, owing to their signed nature, remarkably enhances the possibility of a robust assignment of the experimental absorption bands.

Chiroptical inversion for isolated vibronic transitions of supersonic beam-cooled molecules.

Circular dichroism-resonance-enhanced multiphoton ionization (CD-REMPI) was used for CD measurements on several single vibronic transitions of supersonic beam-cooled (R)-(+)-1-phenylethanol. Due to the low molecular densities within a supersonic beam and the expected small anisotropy factor of 1-phenylethanol in the permille region, the precision of the experimental method had to be significantly improved. Therefore, a single laser pulse evaluation combined with a twin-peak technique enabled within the used supersonic beam setup is presented.

Time-of-flight mass spectrometry: Introduction to the basics.

The intention of this tutorial is to introduce into the basic concepts of time-of-flight mass spectrometry, beginning with the most simple single-stage ion source with linear field-free drift region and continuing with two-stage ion sources combined with field-free drift regions and ion reflectors-the so-called reflectrons. Basic formulas are presented and discussed with the focus on understanding the physical relations of geometric and electric parameters, initial distribution of ionic parameters, ion flight times, and ion flight time incertitude. This tutorial is aimed to help the applicant to identify sources of flight time broadening which limit good mass resolution and sources of ion losses which limit sensitivity; it is aimed to stimulate creativity for new experimental approaches by discussing a choice of instrumental options and to encourage those who toy with the idea to build an own time-of-flight mass spectrometer.

Mass-Selected Circular Dichroism of Supersonic-Beam-Cooled [D ]-(R)-(+)-3-Methylcyclopentanone.

UV spectroscopy and electronic circular dichroism (ECD) experiments on supersonic-beam-cooled deuterated (R)-(+)-3-methylcyclopentanone ([D ]-(R)-(+)-3-MCP) have been performed by using a laser mass spectrometer. The spectral resolution not only allowed excitation and CD measurements for single vibronic transitions but also for the rotational P, Q, and R branches of these transitions. The investigated n→π*18042501 transition showed the largest anisotropy factor ever observed for chiral molecules in the gas phase, which, due to residual saturation of the excited transition, represents only a lower limit for the real anisotropy factor.

Mass-Selective Chiral Analysis.

Three ways of realizing mass-selective chiral analysis are reviewed. The first is based on the formation of diastereomers that are of homo- and hetero- type with respect to the enantiomers of involved chiral molecules. This way is quite well-established with numerous applications.

Laser mass spectrometry with circularly polarized light: circular dichroism of cold molecules in a supersonic gas beam.

An experiment on chiral molecules that combines circular dichroism (CD) spectroscopy, mass-selective detection by laser mass spectrometry (MS), and cooling of molecules by using a supersonic beam is presented. The combination of the former two techniques (CD-laser-MS) is a new method to investigate chiral molecules and is now used by several research groups. Cooling in a supersonic beam supplies a substantial increase in spectroscopic resolution, a feature that has not yet been used in CD spectroscopy.

Dynamic Oil Consumption Measurement of Internal Combustion Engines using Laser Spectroscopy.

A new approach has been developed to measure dynamic consumption of lubricant oil in an internal combustion engine. It is based on the already known technique where sulfur is used as a natural tracer of the engine oil. Since ejection of motor oil in gaseous form into the exhaust is by far the main source of engine oil consumption, detection of sulfur in the exhaust emission is a valuable way to measure engine oil consumption in a dynamic way.

Communication: In search of four-atom chiral metal clusters.

A combined study utilizing anion photoelectron spectroscopy and density functional theory was conducted to search for four-atom, chiral, metal, and mostly metal clusters. The clusters considered were AuCoMnBi(-/0), AlAuMnO(-/0), AgMnOAl(-/0), and AuAlPtAg(-/0), where the superscripts, (-/0), refer to anionic and neutral cluster species, respectively. Based on the agreement of experimentally and theoretically determined values of both electron affinities and vertical detachment energies, the calculated cluster geometries were validated and examined for chirality.

Resonance-enhanced multiphoton ionization with circularly polarized light: chiral carbonyls.

An introduction to the principle and possibilities of the new method of circular dichroism laser mass spectrometry is given and its state of development is reviewed. This method allows enantiosensitive, mass-selective probing of chiral molecules. It is based on the combination of resonance-enhanced multiphoton ionization with circularly polarized light and specially modified time-of-flight mass spectrometry.

Laser mass spectrometry with circularly polarized light: circular dichroism of molecular ions.

In recent experiments of resonance-enhanced laser ionization, large differences between circular dichroism measured for molecular and fragment ions were found by several research groups for different molecular systems. In the case of 3-methylcyclopentanone (3-MCP) we attributed this effect to a large circular dichroism of the molecular ion. In the work presented here, this effect in 3-MCP is studied by ion spectroscopy, by varying the neutral intermediate excited state involved in resonance-enhanced multiphoton ionization (REMPI) and by performing REMPI-induced measurements of circular dichroism at different laser pulse energies.

Laser mass spectrometry with circularly polarized light: two-photon circular dichroism.

Extensive studies of two-photon circular dichroism (TPCD) on 3-methylcyclopentanone are presented following the first TPCD experiment of gas phase molecules by Compton et al. [J. Chem.

Multiphoton ionization and circular dichroism: new experimental approach and application to natural products.

Enantio-sensitive laser mass spectrometry is the combination of multiphoton ionization by circularly polarized laser light with mass spectrometric detection of ions. The method has been developed as a tool for the fast investigation of chiral molecules in sample mixtures without any preceding separation and offers many new experimental possibilities. The main difficulties of the detection of circular dichroism in this way arise from systematic and statistical deviations.

Anion ZEKE-spectroscopy of the weakly bound iodine water complex.

Zero kinetic electron energy photodetachment spectroscopy of I(-)·H(2)O and I(-)·D(2)O has been performed from 27 660 to 28 500 cm(-1) and from 27 660 to 35 900 cm(-1), respectively. The I(-)·D(2)O spectral data and theoretical studies resulted in a reassignment of earlier anion-ZEKE spectra of iodide water ( Bässmann , C. ; et al.

Photodetachment-photoelectron spectroscopy of HS- x H2S and DS- x D2S: the transition states of the SH + H2S and SD + D2S reactions.

The transition state region for neutral hydrogen transfer reactions can be accessed by photodetachment of a stable negative ion with a geometry similar to that of the neutral transition state. In this work the SH + H(2)S and SD + D(2)S reactions are investigated by photodetachment-photoelectron spectroscopy of HS(-) x H(2)S and DS(-) x D(2)S. The spectra exhibit vibrational structure which is attributed to the antisymmetric stretching mode (H-atom motion) of the neutral transitions state for H-atom transfer.

Progress in circular dichroism laser mass spectrometry.

Circular dichroism in ion yield has promising new potentials for chiral analysis. Our progress of its development is described here. Circular dichroism in ion yield is achieved by resonance-enhanced multiphoton ionization.

Photodetachment-photoelectron spectroscopy of disulfanide: the ground and first excited electronic state of HS2 and DS2.

Photodetachment-photoelectron spectra of HS(2)(-) and DS(2)(-) are presented. The obtained electron affinities (EA (HS(2)) = 1.916 +/- 0.

The weakly-bound complex Cl.N2O studied by high resolution photodetachment photoelectron spectroscopy.

Zero kinetic energy photoelectron spectroscopy of the weakly bound complex Cl(-).N(2)O is presented. Adiabatic detachment energies between the anionic complex and the neutral complex states X(1/2), I(3/2), and II(1/2) as well as frequencies of van der Waals modes are supplied.

The electron affinity of phenanthrene.

Phenanthrene is studied by photodetachment-photoelectron spectroscopy. Due to the absence of a parent ion peak in the anion mass spectrum the electron affinity could not be determined directly. However, this absence is the first indication that this molecule has a negative electron affinity.

A new approach for fast, simultaneous NO/NO2 analysis: application of basic features of multiphoton-induced ionization and dissociation of NO(x).

A new method of simultaneously recording NO and NO2 concentrations in complex gas mixtures is described. This method is based on resonance enhanced multiphoton ionization (REMPI), on time-of-flight mass analysis, and on monitoring the kinetic energy released upon dissociation of NO2. Its benefits are high speed and high flexibility.

Mobile resonance enhanced multiphoton ionisation-time-of-flight mass spectrometer with a novel hybrid laser desorption/molecular beam ion source for rapid detection of aromatic trace compounds from gas phase and solid samples.

A mobile, field applicable resonance enhanced multiphoton ionisation-time-of-flight mass spectrometer (REMPI-TOFMS) for direct-inlet gas-phase analysis as well as for characterisation of solid samples, has been developed. For solid-sample analysis, laser desorption (LD) with IR-laser pulses is used for volatilisation of the neutral analytes from a target in the ion source prior to REMPI-TOFMS analysis. For direct inlet gas-phase analysis, a needle gas inlet is used and the formed molecular beam is REMPI-ionised directly in the ion source.

Mass-selected resonance-enhanced multiphoton ionisation spectra of laser-desorbed molecules for environmental analysis: 16 representative polycyclic aromatic compounds.

Mass-selected gas-phase UV spectra of laser-desorbed molecules at room temperature have been measured via resonance-enhanced multiphoton ionisation (REMPI) and time-of-flight mass selection. The wavelength range of 260 to 320 nm is optimal for detection of polycyclic aromatic hydrocarbons (PAHs) using REMPI-mass spectrometry. A new laser desorption/laser ionisation source has been used which features a compact size and thermal equilibrium of the desorbed molecules.

Mass selective gas phase study of ClO, OClO, ClOO and ClAr by anion-ZEKE-photoelectron spectroscopy.

Anion-ZEKE-photoelectron spectra of ClO-, OClO-, ClOO- and the van der Waals cluster ArCl- have been measured. Refined or new values for the electron affinity of ClO, OClO and ClOO have been found. The peak positions in these spectra are in very good agreement with former ClO- and OClO- anion-photoelectron spectra (K.

Laser mass spectrometry for environmental and industrial chemical trace analysis.

Resonant laser mass spectrometry is a promising method for chemical trace analysis since it combines selectivity, sensitivity and rapidity of measurement. It is a two-dimensional technique incorporating medium- or high-resolution UV spectroscopy and time-of-flight mass spectrometry. No sample preparation and chemical clean-up is necessary to reach detection limits in the sub-ppb range even when highly complicated mixtures of chemical species are analyzed.

On-Line Emission Analysis of Polycyclic Aromatic Hydrocarbons down to pptv Concentration Levels in the Flue Gas of an Incineration Pilot Plant with a Mobile Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometer.

A newly developed, mobile laser mass spectrometer (resonance-enhanced multiphoton ionization - time-of-flight mass spectrometer, REMPI-TOFMS) was applied to on-line measurements at a waste incineration pilot plant. REMPI-TOFMS combines the optical selectivity of resonance-enhanced multiphoton ionization with a time-of-flight mass analysis to give a two-dimensional analytical method. Special care was taken to build up a sampling and inlet system suitable for on-line measurements of large, semivolatile polycyclic aromatic hydrocarbons (PAHs).