Intracavity laser absorption spectroscopy

Figure 10 shows the schematics of the experimental setup used for intracavity laser absorption spectroscopy (ICLAS) of bilayer lipid membranes (BLMs). Simultaneous electrical and ICLAS measurements were carried out in a two-compartment container constructed from two 1 cm path lengths quartz cells (Figure 11). 

Figure 10. Schematics of the experimental setup for intracavity laser absorption spectroscopy (ICLAS). CD chopper driver PM power meter Mj, M2, M3, M4 spherical high reflection mirrors Mp = pump mirror MN monochromator PMT photomultiplier SP silicon photocell PC Pockels cell WF wedged filter LIA lock-in amplifier R recorder MS microscope OF optical fiber S sample (solution on BLM) IEM instruments for electrical measurements (see Figure 2).

In this section, we will review previous studies of the CH overtone spectroscopy of CD3H. There exist high-resolution, rotationally resolved, experimental data for the first three CH overtones ( uv,) with n = 2, 3, 4) in the infrared and near infrared region (91,94). In the visible region, there also exists data from photoacoustic laser spectroscopy (96,97) and from the intracavity laser absorption spectroscopy (ICLAS) technique, which provides absolute intensities (85,86). Compared to methane, analysis of the spectra is much easier for CD3H, because of the relatively isolated CH chromophore. 

The near-infrared electronic transition occurring in the region of 745 nm was originally assigned as connected to the ground state. O Brien et al. [OOOBr] have recorded and analyzed this transition using intracavity laser absorption spectroscopy and conclude that it occurs between two unknown excited states. 

J. Cheng et al.. Infrared intracavity laser absorption spectroscopy with a continuous-scan Fourier-transform interferometer. Appl. Opt. 39(13), 2221 (2000)... 

Handler KG, Harris RA, O Brien LC, O Brien JJ (2011) Intracavity laser absorption spectroscopy of platinum fluoride, PtF. J Mol Spectr 265 39- 6... 

The main part of the book presents various applications of lasers in spectroscopy and discusses the different methods that have been developed recently. Chapter 6 starts with Doppler-limited laser absorption spectroscopy with its various high-sensitivity detection techniques such as frequency modulation and intracavity spectroscopy, cavity ring-down techniques, excitation-fluorescence detection, ionization and optogalvanic spectroscopy, optoacoustic and optothermal spectroscopy, or laser-induced fluorescence. A comparison between the different techniques helps to critically judge their merits and limitations. 

Fiq.l0.24a-c. Intracavity saturated absorption spectroscopy, (a) Experimental setup, (b) "Lamb peak" in the laser output, (c) derivative of a Lamb peak obtained by modulation of the laser frequency... 

Goldman, A. et al.. Fiber laser intracavity absorption spectroscopy of ammonia and hydrogen cyanide in low pressure hydrocarbon flames, Chem. Phys. Lett., 423, 147, 2006. 

Intracavity enhancement, relative to conventional single pass absorption spectroscopy, is due to mode competition and to threshold effects. A simple calculation of the latter for a single mode laser, starting with... 

Fig. 1.15 Time evolution of the spectral profile of the laser output measured with time-resolved intracavity absorption spectroscopy [13]...

Fig. 1.16 Isotope-selective intracavity absorption spectroscopy. The frequencies (Ok absorbed by the isotope inside the laser cavity are missing in the laser output, which therefore does not excite any fluorescence in the same isotope outside the laser resonator [20]...

All these techniques may be combined with intracavity absorption when the sample molecules are placed inside the laser resonator to enhance the sensitivity. Cavity ring-down spectroscopy yields absorption spectra with a detection sensitivity that is comparable to the most advanced modulation techniques in multipass absorption spectroscopy. 

V.M. Baev, T. Latz, P.E. Toschek, Laser intracavity absorption spectroscopy. Appl. Phys. B 69,171 (1999) ... 

E.A. Sviridenko, M.P. Erolov, Possible investigations of absorption line profiles by intracavity laser spectroscopy. Sov. J. Quantum Electron. 7, 576 (1977)... 

B. Lohden, S. Kuznetsova, K. Sengstock, V.M. Baev, A. Goldman, S. Cheskis, B. Pdlsd6ttir, Fiber laser intracavity absorption spectroscopy for in situ multicomponent gas analysis in the atmosphere and combustion environments. Appl. Phys. B, Lasers Opt. 102, 331-344 (2011)... 

Applications So far, intracavity laser spectroscopy has been applied primarily to the detection of absorption spectra of gaseous impurities such as NH3 and CH4 in the near-infrared region using a tunable broadband laser. Special DLs designed with an external cavity have also been investigated recently for this purpose. CRS has been applied successfully to trace element detection using the ICP as the atomization system. The detection limits observed are at sub-parts per billion level (e.g., 0.3 ng ml for lead) and comparable to the detection limits achieved with ICP-MS. 

E.N. Antonov, V.G. Koloshnikov, V.R. Mironenko Quantitative measurement of small absorption coefficients in intracavity absorption spectroscopy using a cw-dye laser. Opt. Commun. 15, 99 (1975)... 

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