Laser wavenumber

Figure 9.22 illustrates how a CARS experiment might be carried out. In order to vary (vj — V2) in Equation (9.18) one laser wavenumber, Vj, is fixed and V2 is varied. Here, Vj is frequency-doubled Nd YAG laser radiation at 532 nm, and the V2 radiation is that of a dye laser which is pumped by the same Nd YAG laser. The two laser beams are focused with a lens L into the sample cell C making a small angle 2a with each other. The collimated CARS radiation emerges at an angle 3 a to the optic axis, is spatially filtered from Vj and V2... 

In Eq. (9-3), the first term describes Rayleigh scattering at the incident laser wavenumber, the second term is Stokes Raman scattering at wavenumber v(> — vk and the third term is anti-Stokes Raman scattering at wavenumber v0 + vk. 

The fine structure interval AEqi is obtained from the laser wavenumber and the ion beam velocity using the relativistic Doppler formula. To caUbrate the 90° analysing magnet we tuned a beam from the tandem accelerator,... 

Sample Paramotors Raman Laser Wavenumber Raman Laser Power In mW 9394.000000 500.000000... 

An inverted version of the messenger tagging technique for detecting ion absorption uses the fact that electronic and/or vibrational excitation of ions hinders formation of weakly-bound clusters. This effect, explored years ago in relation to laser isotope separation [82], has recently been demonstrated for spectroscopy of N2" ions, cooled to 10.6 K in a 22-pole trap by collisions with He and termed laser-induced inhibition of cluster growth (LIICG) [83]. An electronic spectrum is generated by monitoring the reduction of the steady-state concentration of ion-He complexes as a function of the excitation laser wavenumber. 

Fig. 16 Photofragmentation mass spectra of [GS+2H] (m/z = 571.36 Da) measured with the UV laser only (blue trace) and with subsequent CO2 laser excitation (red trace). The UV laser wavenumber is fixed at il.ll i. i cm (the band origin of conformer A, see Fig. 19). Two of the most abundant fragments in the UV photofragmentation mass-spectrum correspond to loss of CO and CO-NH neutral fragments. The two most abundant fi agments in the UV + CO2 mass-spectrum correspond to the loss of a CO group (w/z = 557.3 Da) and to cleavage of the C -Cp bond of a phenylalanine residue (m/z = 525.8 Da)...

Figure 17 shows electronic spectra of the doubly-protonated GS measured by monitoring fragments with miz = 557 as a function of the UV laser wavenumber. The spectra were obtained at the lowest trap temperature of 6 K (Fig. 17a) and under... 

Fig. 18 IR-UV depletion spectra of doubly protonated GS (a) conformer A (b) conformer B (c) conformer C measured by fixing UV laser wavenumber on their respective peaks A1-A4, B and C (the largest peak only) in Fig. 18...

Figure 18 shows IR-UV depletion spectra of [GS + 2H] measured by fixing the UV laser wavenumber to transitions assigned to conformers A, B, and C in the spectrum of Fig. 17a. Each IR spectrum reflects the specific vibrational frequencies associated with the different conformers giving rise to the probed UV transitions. Several IR bands in the spectrum of conformer A appear to be doubly degenerate. For example, the five peaks lying between 1,600 and 1,700 cm belong to the ten bands that have primarily C=0 stretch character. This double degeneracy implies that pairs of oscillators are situated in equivalent positions in the molecule, and since GS is cyclic, this conformer must have C2 symmetry [158].

Color-center laser The tunable wavenumber region is about 12 500-2500 cm . As the laser wavenumber can be very accurately controlled, this laser is used for high-resolution, time-resolved measurements of the gaseous state. 

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