Thermal ionization cavity

Wayne DM, Hang W, McDaniel DK, Fields RE, Rios E, Majidi V (2002) The thermal ionization cavity (TIC) source elucidation of possible mechanisms for enhanced ionization efficiency. Inti J Mass Spectrom 216 41-57... 

Schematic representation of a thermal ionization cavity source.

Buerger, S., et al. (2007) A high efficiency cavity ion source using thermal ionization mass spectrometry (TIMS) for nuclear forensic analysis. Journal of Alloys and Compounds, 444-445, 660-662. 

Fig. 10.2 Major components of a thermal atomic beam apparatus for microwave ionization experiments,the atomic source, the microwave cavity, and the electron multiplier. The microwave cavity is shown sliced in half. The Cu septum bisects the height of the cavity. Two holes of diameter 1.3 mm are drilled in the side walls to admit the collinear laser and Na atomic beams, and a 1 mm hole in the top of the cavity allows Na+ resulting from a field ionization of Na to be extracted. Note the slots for pumping (from ref. 4).

The second approach is to use thermal beams of alkali atoms as shown in Fig. 10.2.4 A beam of alkali atoms passes into a microwave cavity where the atoms are excited by pulsed dye lasers to a Rydberg state. A1 /zs pulse of microwave power is then injected into the cavity. After the microwave pulse a high voltage pulse is applied to the septum, or plate, inside the cavity to analyze the final states after interaction with the microwaves. By adjusting the voltage pulse it is possible to detect separately atoms which have and have not been ionized or to analyze by selective field ionization the final states of atoms which have made transitions to other bound states. 

A simplified view of the early processes in electron solvation is given in Fig. 9 (i) the electron is ejected from a molecule upon ionization by radiolysis or photolysis (ii) in the thermalization step, the ejected electron progressively loses its excess kinetic energy in collisions with solvent molecules (iii) then, the electron is localized, trapped in a solvent site or cavity and (iv) becomes solvated when the solvent molecules have obtained their equilibrium configuration after relaxation. 

Fig. 9.7 Various resonant photoionization techniques for ultrasensitive spectroscopy of very rare atoms and isotopes (a) ionization of a transverse thermal atomic beam (b) ionization of atoms in a buffer gas (c) ionization of atoms trapped in a hot cavity (d) ionization of...

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