REMPI-TOF

FIGURE 11.25 Schematic of REMPI-TOF. The conventional electron impact ionization source is just used for ion beam focusing (adapted from Schmidt et al., 1999). 

Vibrational spectra of aniline/cyclohexane and aniline/benzene clusters investigated by infrared depletion spectroscopy with selective resonance—enhanced multiphoton ionization with time-of-flight mass spectrometry (REMPI-TOF mass spectrometry) show186 an... 

Figure 1.10 REMPI-TOF permits selective simultaneous recording of separate spectra for different cluster species or for different isotopomers. The spectra of NiC and NiSi were recorded (by resonant two-photon ionization using an ArF excimer laser to ionize) using laser ablation of a nickel target in a stream of carrier gas containing 3% CH4. No intentional source of silicon was present (but the nickel sample had been roughened using SiC sandpaper) (from Brugh and Morse, 2002, and Lindholm, et al, 2003).

Figure 1.14 Simultaneously recorded REMPI-TOF spectra of several isotopomers of MoC. Spectra (b) - (f) correspond, respectively, to 98MoC (24.1% natural abundance), 97MoC (9.6%), 96MoC (16.7%), 9SMoC (15.9%), and 94MoC (9.3%). Spectrum (a) is the sum of spectra (b) - (f). It is not the spectrum that would have been obtained without TOF mass-selectivity because the summation does not include the spectra of 92MoC (14.8%) and 100MoC (9.6%) (from D. Brugh, Ph.D. thesis, 1997, courtesy of M. Morse see also Brugh, et at., 1998).

Figure 3.5. (1+1)-REMPI TOF-MS of Si atoms obtained by tuning a frequency-doubled dye laser through the 4s

Figure 9.5 Typical REMPI-TOF mass spectra from the molecular beam reaction Ca+H2/D2 recorded for the CaH/CaD(X-B, 0-0) Pi(l) transition line. Bottom trace excitation off middle trace CaH-excitation on top trace CaD-exdtationon.Tracesareoffsetfromeachotherforclarity...

Another issue in trap-loss detection is the competition between homonuclear and heteronuclear trap loss in a given experiment, making assignments quite difficult. For example, when searching for KRb trap loss just below the %i/2 + 5pi/2 asymptote, stronger trap loss is simultaneously observed from just below the Rb2 5 i/2 + 5pi/2 asymptote. However, for detection of KRb+ ions by REMPI from theX and/or a states of KRb, there is no competition from ions due to Rb2 PA (the Rb+ and RbJ ions are easily distinguishable by their differing TOFs). Thus we believe that REMPI TOF mass spectrometer detection of X- and a-state heteronuclear molecules is normally preferable to trap-loss spectroscopy. 

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