Spectroscopy photodetachment

The above fomuilae for the absorption spectrum can be applied, with minor modifications, to other one-photon spectroscopies, for example, emission spectroscopy, photoionization spectroscopy and photodetachment spectroscopy (photoionization of a negative ion). For stimulated emission spectroscopy, the factor of fflj is simply replaced by cOg, the stimulated light frequency however, for spontaneous emission... 

Gantefor G, Meiwes-Broer K H and Lutz H O 1988 Photodetachment spectroscopy of cold aluminum cluster anions Phys. Rev. A 37 2716... 

A second role for mass spectrometry in the investigation of reactive intermediates involves the nse of spectroscopy. Althongh an important nse of ion spectroscopy is the determination of thermochemical properties, including ionization energies (addition or removal of an electron), as in photoelectron or photodetachment spectroscopy, and bond dissociation energies in ions, as in photodissociation methods, additional spectroscopic data can also often be obtained, inclnding structural parameters such as frequencies and geometries. 

DETERMINATION OF MAGNETIC MOMENTS BY COMBINING THEORY AND PHOTODETACHMENT SPECTROSCOPY... 

Photodetachment spectroscopy of negative ions like IHI- and similar systems, studied by Neumark and coworkers (Metz, Kitsopoulos, Weaver, and Neumark 1988 Weaver, Metz, Bradforth, and Neumark 1988 Metz et al. 1990 Bradforth et al. 1990 Neumark 1990 Weaver and Neumark 1991) has provided the first conclusive manifestation of reactive resonances for a purely repulsive PES. The idea of the experiment goes as follows a photon with frequency u detaches the electron from the negative ion producing e- and IHI. If the PES for the neutral molecule is dissociative, the IHI complex subsequently breaks apart into I and HI. 

The electron affinity (31.9 0.7 kcalmoH ) and gas-phase acidity (361.5 2.8 kcalmoH ) for MesGeH have been determined using photodetachment spectroscopy. The bond dissociation energy (Ge-H) derived from these values was determined to be 79.8 3.5 kcalmoH, in excellent agreement with other determinations. ... 

We present the results of experimental studies of photon-negative ion interactions involving the dynamics of two electrons. Resonances associated with doubly excited states of Li and He" have been observed using laser photodetachment spectroscopy. Total and partial photodetachment cross sections have been investigated. In the former case, the residual atoms are detected irrespective of their excitation state, while in the latter case only those atoms in specific states are detected. This was achieved by the use of a state selective detection scheme based on the resonant ionization of the residual atoms. In addition, in the case of Li-photodetachment, the threshold behavior of the Li(2 P)+e-(ks) partial cross section has been used to accurately measure the electron affinity of Li. 

Molecular anions, AB, have also been studied for many years by various forms of photoelectron and photodetachment spectroscopy,... 

Yourshaw I, Zhao Y and Neumark D M 1996 Many-body effects in weakly bound anion and neutral clusters zero electron kinetic energy spectroscopy and threshold photodetachment spectroscopy of Ar Br" n = 2-9) and Ar r (n =... 

The combination of MD/DF calculations and photodetachment spectroscopy provides a useful approach to the problem of determining the structure of atomic clusters. The PACIS provides a flexible method for generating clusters of many materials and for performing photoelectron spectroscopy on them. The elements include metals (solid and liquid), semiconductors, and highly reactive materials such as phosphorus. There is little doubt that the source will provide interesting data for many other systems. For the analysis of these data, or for predictions of interesting systems for study, the MD/DF approach should prove to be an ideal tool. 

Similar experiments, involving electron transfer between an anion and a neutral molecule, yield relative or absolute EAs. The method has been used to determine relative free energies for electron attachment for a variety of metallocenes and /3-diketonate molecules. Electron photodetachment spectroscopy of negatively charged ions is another source for obtaining electron affinities of molecules. These data provide an important component of thermochemical cycles involving oxidation/reduction of metal complexes, and serve as a basis for obtaining other thermochemical values. 

Another group of experiments based on the coaxial arrangement deals with photodetachment spectroscopy of the negative molecular ions [9.84]. Negative molecular ions play an important role in the upper atmosphere and in many chemical reactions. Although hundreds of bound molecular negative ions are known, very few have been measured with rotational resolution. 

Since the extra electron generally has a low binding energy, most negative ions can be ionized (photodetachment) by visible or infrared lasers. The remaining ions are separated from the neutral molecules formed in the photodetachment process by a deflecting electric field. An example of sub-Doppler photodetachment spectroscopy of can be found in [9.85]. 

Zhang DH, Yang M, Collins MA, Lee S-Y (2002) Probing the transition state via photoelectron and photodetachment spectroscopy of HsO . Proc Natl Acad Sd USA 99 11579... 

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