Photodetachment photoelectron spectroscopy

Wang L S 2000 Photodetachment photoelectron spectroscopy of transition metal oxide species Photoionization and Photodetaohment Advanced Series in Physical Chemistry 10, ed C Y Ng (Singapore World Scientific)... 

Determination of the Singlet-Triplet Gap in TMM by Electron Photodetachment Photoelectron Spectroscopy ... 

A non-Kekule molecule conceptually formed by fusion of two TMM units and also predicted" " to have a triplet ground state is 2,4-dimethylenecyclo-butane diyl (20), which ultimately was prepared by two independent syntheses. Matrix ESR spectroscopy and gas-phase photodetachment photoelectron spectroscopy (PES) (see Section 4.1.4) eventually agreed that the ground state is triplet. 

The electronic structure of several model complexes for mononuclear iron proteins has been evaluated by gas-phase photodetachment photoelectron spectroscopy. Molecules of interest are negatively charged, such as Fe(SCN)3, Fe(SCN)4, and Fe(SCN)4. The anions were transported into the gas phase by electrospray ionization isolated Fe(SCN)4 was not detected in the gas phase, but rather was trapped as the stabilized ion pair Na+ [Fe(SCN)4 ]. 

Here we present the results of P3 studies of the VDEs of the most stable conformation of a dinucleotide—2, 2 -deoxyribodithymidine-3, 5 -monophosphate anion (dDTMP- or dTT-). The choice of this particular dinucleotide was dictated by (1) the availability of electrospray photodetachment photoelectron spectroscopy data, (2) the relatively small size of dTT-, and (3) the lack of tautomeric transitions in the parent nucleobase, thymine. The structure depicted in Figure 1 seems to be a global minimum. It was found among numerous conformations of dTT- by means of, first, molecular mechanics analysis and, second, reoptimization of the structures with the B3LYP/ 6-311 + + G model. The structure shown in Figure 1 is characterized by two H bonds between one of the phosphate oxygens and the two... 

TABLE 8.2 Atomic Electron Affinities (in eV) Determined by Photodetachment, Photoelectron Spectroscopy and Surface Ionization Techniques [4, 7 12]... 

Electron detachment from anionic mono-, di-, and trinucleotides was studied experimentally by electrospray photodetachment photoelectron spectroscopy (EPPS) [74]. Substrates did not decompose at the relatively low temperatures of these experiments. 

From a historical perspective, the first unambiguous observation of dipole states came from the group of Kit Bowen (Johns Hopkins) in 1990, who studied the important water dimer dipole anion. The Bowen group has also studied ground state dipole-bound anions produced by electron attachment under high-pressure nozzle-jet expansion condition. They have also used photodetachment photoelectron spectroscopy to determine electron affinities for a number of the molecules shown in Figure 4. 

When treating ion spectroscopy one should not forget anions. Similar spectroscopic techniques may be used as for cation spectroscopy. For instance dissociation spectroscopy is also possible for molecular anions. Since excited anionic electronic states mostly do not exist, one uses infrared multiphoton dissociation to study vibrational levels of the ground state. Another interesting technique is the photoelectron spectroscopy of anions (photodetachment photoelectron spectroscopy), which exhibit a very specific feature. This technique differs from cation <— neutral photoelectron spectroscopy in two respects (i) the final state is a neutral one thus anion photoelectron spectroscopy delivers information about neutrals rather than ionic systems, (ii) The initial state is anionic thus mass selection before spectroscopy is possible. As a result, mass selective spectroscopic information of neutral molecular systems is supplied which otherwise is not accessible. This is of particular interest for neutral systems which are only available in complex mixtures or are short-lived intermediate reaction products or radicals. 

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