Photodissociation methods

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. 

APPI and corona discharge-APCI methods were compared [164], A review of photoionisation and photodissociation methods in MS has appeared [165]. 

CID methods have proven to be very useful in measuring the stabilities of clusters of bare transition metal atoms, providing many more thermochemical values than photodissociation methods. In our laboratory, we have used CID to study the cationic clusters of ten different transition metal elements, including TiJ (x=2-22),VJ (x=2-20), CrJ (x=2-21),Mn, FeJ (x=2-19),CoJ (x=2-18),NiJ (x=2—18), and CuJ the second row transition metal clusters of NbJ (x=2-ll) and the third row transition metal clusters of Taj (x=2-4). These results have been summarized and trends analyzed previously [176,177]. CID methods have also been used by Ervin et al. to measure the stabilities of anionic clusters of the coinage metals Cu (x=2-8) [178], Ag (x=2—11) [179], and Au (x=2-7) [180] and group 10 metals Pd [181] and Ptx (x=3-6) [182]. A multiple collision-in-... 

Properties of the complexes of alkali metal cations with various bases are important in understanding ion-molecule interactions, solvation effects, biomedical and physiological phenomena related to ion channels and relevant in medical treatments. Reliable experimental bond dissociation enthalpies, and thereby gas-phase alkali ion affinities, could now be obtained using various mass spectrometry techniques such as the Fourier-transform ion cyclotron resonance (FT-ICR), collision-induced dissociation and photodissociation methods. However, these methods do not provide direct information on the adduct structures. 

The average cross section for a rotationaUy thermal distribution in the v =0 level of the A A state of CH has also been measured at elevated temperature in the LP/LF apparatus [22]. Here, a comparison could be made with cross sections determined from a photodissociation method at room temperature [23]. For the four coUiders common to both experiments, gq increased from 25% to tenfold, in going from 300 K to 1300 K. This behaviour is markedly different from that of OH. 

Photoionization and Photodissociation Methods in Mass Spectrometry Plasma Desorption Ionization in Mass Spectrometry... 

See also Environmental Applications of Eiectronic Spectroscopy Fragmentation in Mass Spectrometry ion Dissociation Kinetics, Mass Spectrometry ion Energetics in Mass Spectrometry Laser Appiications in Eiectronic Spectroscopy Metastabie ions Muitipho-ton Spectroscopy, Appiications Negative ion Mass Spectrometry, Methods Photoeiectron-Photoion Coincidence Methods in Mass Spectrometry (PEPiCO) Photoionization and Photodissociation Methods in Mass Spectrometry Spectroscopy of ions Time of Flight Mass Spectrometers. 

See also Laser Applications in Electronic Spectroscopy Laser Spectroscopy Theory Light Sources and Optics Multiphoton Excitation in Mass Spectrometry Muitiphoton Spectroscopy, Applications Optical Frequency Conversion Pharmaceuticai Appiications of Atomic Spectroscopy Photoelectron Spectroscopy Photoionization and Photodissociation Methods in Mass Spectrometry Pyroiysis Mass Spectrometry, Methods Time of Flight Mass Spectrometers X-Ray Spectroscopy, Theory Zero Kinetic Energy Photo-eiectron Spectroscopy, Appiications Zero Kinetic Energy Photoelectron Spectroscopy, Theory. 

See also Ion Energetics in Mass Spectrometry Ion Imaging Using Mass Spectrometry Ion Structures in Mass Spectrometry Isotopic Labelling in Mass Spectrometry Metastable Ions Photoionization and Photodissociation Methods in Mass Spectrometry Stereochemistry Studied Using Mass Spectrometry. 

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