Laser-Induced Ion formation

Thomson, D. S., A. M. Middlebrook, and D. M. Murphy, "Thresholds for Laser-Induced Ion Formation from Aerosols in a Vacuum Using Ultraviolet and Vacuum-Ultraviolet Laser Wavelengths, Aerosol Sci. Technol., 26, 544-559 (1997). 

Processes of Laser-Induced Ion Formation in Mass Spectrometry... 

Hillenkamp, F. Laser induced ion formation from organic solids. Sprin. Ser. in Chem. Phys. 1983, 25, 190-205. 

The development of laser ionization mass spectrometry was started by Honig and Woolston in 196359 with studies of laser beam sohd surface interaction and ion formation processes. Due to the pulse character of laser-induced ions, ToF analyzers were coupled to laser ion sources in the seventies and produced commercially as LAMMA-500 and later LAMMA-1000 and 2000 (Leybold-Heraeus, Cologne, Germany). 

This paper contains a discussion of the most important features of laser-induced-ion spectra and mechanisms of ion formation, some of them experimentally proven, some of them still under discussion and investigation. Special attention will be given to the LAMMA technique, because this is the authors own field of work, but reference to other systems will be included where appropriate. 

The hydrolysis of the uranyl(VI) ion, UO " 2> has been studied extensively and begins at about pH 3. In solutions containing less than lO " M uranium, the first hydrolysis product is the monomeric U02(OH)", as confirmed using time-resolved laser induced fluorescence spectroscopy. At higher uranium concentrations, it is accepted that polymeric U(VI) species are predominant in solution, and the first hydrolysis product is then the dimer, (U02)2(0H) " 2 (154,170). Further hydrolysis products include the trimeric uranyl hydroxide complexes (U02)3(0H) " 4 and (1102)3(OH)(154). At higher pH, hydrous uranyl hydroxide precipitate is the stable species (171). In studying the sol-gel U02-ceramic fuel process, O nmr was used to observe the formation of a trimeric hydrolysis product, ((U02)3( -l3-0)(p.2-0H)3) which then condenses into polymeric layers of a gel based on the... 

Some physical techniques can be classified into flame treatments, corona treatments, cold plasma treatments, ultraviolet (UV) treatment, laser treatments, x-ray treatments, electron-beam treatments, ion-beam treatments, and metallization and sputtering, in which corona, plasma, and laser treatments are the most commonly used methods to modify silicone polymers. In the presence of oxygen, high-energy-photon treatment induces the formation of radical sites at surfaces these sites then react with atmospheric oxygen forming oxygenated functions. 

Neumann, R., Poth, H., Winnacker, A. and Wolf, A. (1983). Laser-induced electron-ion capture and antihydrogen formation. Z. Phys. A 313 253-262. 

Steroids (neutral or conjugated) and their dansylhydrazine derivatives Polyacrylic gel-based macroporous particles Acetonitrile-water-240 mM ammonium formate buffer, pH 3 (55 40 5) (also gradient elution) 350 mm x 100 pm i.d. 250 mm active length, laser induced fluorescence detection or coupling with electrospray-ion-trap mass spectrometry... 

The influence of the laser and plasma parameters (such as wavelength, laser power density, pulse length, plasma temperature, electron and ion density and others) on the physical and chemical processes in a laser induced plasma with respect to the formation of polyatomic and cluster ions has been investigated for different materials (e.g. graphite, boron nitride, boron nitride/graphite mixture, boron carbide, tungsten oxide/graphite mixture and superconductors ). 

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