Resonance-ionization spectroscopy

James A M, Kowaiczyk P, Langlois E, Campbell M D, Ogawa A and Simard B 1994 Resonant two photon ionization spectroscopy of the molecules Nb, and Nb2 J. Chem. Rhys. 101 4485... 

In other articles in this section, a method of analysis is described called Secondary Ion Mass Spectrometry (SIMS), in which material is sputtered from a surface using an ion beam and the minor components that are ejected as positive or negative ions are analyzed by a mass spectrometer. Over the past few years, methods that post-ion-ize the major neutral components ejected from surfaces under ion-beam or laser bombardment have been introduced because of the improved quantitative aspects obtainable by analyzing the major ejected channel. These techniques include SALI, Sputter-Initiated Resonance Ionization Spectroscopy (SIRIS), and Sputtered Neutral Mass Spectrometry (SNMS) or electron-gas post-ionization. Post-ionization techniques for surface analysis have received widespread interest because of their increased sensitivity, compared to more traditional surface analysis techniques, such as X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES), and their more reliable quantitation, compared to SIMS. 

Sputter-Initiated Resonance Ionization Spectroscopy Surface Analysis by Resonant Ionization Spectroscopy Time-of-Flight Mass Spectrometer... 

REMPI resonance-enhanced multiphoton ionization spectroscopy... 

Mons M, Piuzzi F, Dimicoli I, Gorb L, Lesczynski J (2006) Near-UV resonant two-photon ionization spectroscopy of gas phase guanine evidence for the observation of three rare tautomers. J Phys Chem A 110 10921-10924... 

Resonance ionization spectroscopy is a photophysical process in which one electron can be removed from each of the atoms of a selected type. Since the saturated RIS process can be carried out with a pulsed laser beam, the method has both time and space resolution along with excellent (spectroscopic) selectivity. In a recent article [2] we showed, for example, that all of the elements except helium, neon, argon, and fluorine can be detected with the RIS technique. However, with commercial lasers, improved in the last year, argon and fluorine can be added to the RIS periodic table (see figure 2). 

Charge Neutralization and Resonance Ionization Spectroscopy with Amplification (RISA)... 

This section will focus on the stmcture and energetics of chiral molecular complexes studied with Fourier-transform IR (FT-IR), microwave, LIF, hole burning (HB), IR fluorescence dip spectroscopy, resonance-enhanced multiphoton ionization (REMPl Fig. 5), and RET spectroscopy. 

Resonant and non-resonant laser post-ionization of sputtered uranium atoms using SIRIS (sputtered initited resonance ionization spectroscopy) and SNMS (secondary neutral mass spectrometry) in one instrument for the characterization of sub-pm sized single microparticles was suggested by Erdmann et al.94 Resonant ionization mass spectrometry allows a selective and sensitive isotope analysis without isobaric interferences as demonstrated for the ultratrace analysis of plutonium from bulk samples.94 Unfortunately, no instrumental equipment combining both techniques is commercially available. 

G. Gerber By applying two-photon ionization spectroscopy with tunable femtosecond laser pulses we recorded the absorption through intermediate resonances in cluster sizes Na with n = 3,. 21. The fragmentation channels and decay pattern vary not only for different cluster sizes but also for different resonances corresponding to a particular size n. This variation of r and the fragmentation channels cannot be explained by collective type processes (jellium model with surface plasmon excitation) but rather require molecular structure type calculations and considerations. 

The photolysis of aromatic species with tetranitromethane in perfluoro alcohol solvent has been studied, in which the radical cations were observed by EPR spectroscopy.284 Photo-stimulated reaction of 1- and 2-haloadamantanes and 1,2- and 1,3-dihaloadamantanes with various carbanionic nucleophiles afforded products rationalized through an SrnI mechanism.285 286 Photolysis of the cycloadduct formed between a functionalized derivative of C6o and diazomethane has been shown to afford a pah of ling-opened structures (125) and (126) via a proposed biradical intermediate (127) (Scheme 19). The UV-photolytic fragments of /-butyl iodide (T and /-Bu ) have been ionized by resonance-enhanced multiphoton ionization for TOF mass spectro-metric analysis.287 A two-dimensional position-sensitive detector provided angular distribution and translational energy data. 

Resonance ionization spectroscopy (RIS) with pulsed tunable lasers offers new possibilities for constructing pulsed, highly selective ion sources with high efficiencies. Fig. 4 shows the principle of RIS and the planned set up. The efficiency of the ion source is determined mainly by the ratio of the repetition rate... 

Fig. 4 Right Principle of resonance ionization spectroscopy. Three tunable pulsed Dye lasers are used to stepwize excite and ionize the atom. The effective cross-sections are indicated for the different transitions in cm2. Left Layout of a laser ion source for on-line mass separators.

RESONANCE IONIZATION SPECTROSCOPY IN THERMAL ATOMIC BEAMS ... 

Speranza [108] has developed a methodology to establish the enantiomeric discrimination of chiral monoalcohols and monoamines by mass spectroscopy. The method is based on the generation of supersonically expanded complexes formed by the alcohol or amine and chromophores as either R-(+)-l-phenyl-etanol or R-(+)-l-phenyl-1-propanol. The complexes thus formed, are ionized by R2PI (resonance 2-photon ionization spectroscopy) and their fragmentation studied by time of flight spectroscopy. It is possible to evaluate the enantiomeric discrimination... 

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