Tunable laser spectrometer

SAM consists of several different instrument components, including a tunable laser spectrometer (TLS) and a GC-MS. The TLS will be responsible for the detection of trace volatile gases and their isotopic ratios of such species as D H in H2O, 0 O in H2O and CO2, and in CH4 and CO2 are expected to be mea-... 

Tarsitano, C.G., Webster, C.R. (2007) Multilaser Herriott cell for planetary tunable laser spectrometers. Applied Optics, 46(28), 6923-6935. 

Tunable laser spectroscopic techniques such as laser-induced fluorescence (LIF) or resonantly enhanced multi-photon ionization (REMPI) are well-established mature fields in gas-phase spectroscopy and dynamics, and their application to gas-surface dynamics parallels their use elsewhere. The advantage of these techniques is that they can provide exceedingly sensitive detection, perhaps more so than mass spectrometers. In addition, they are detectors of individual quantum states and hence can measure nascent internal state population distributions produced via the gas-surface dynamics. The disadvantage of these techniques is that they are not completely general. Only some interesting molecules have spectroscopy amenable to be detected sensitively in this fashion, e.g., H2, N2, NO, CO, etc. Other interesting molecules, e.g. 02, CH4, etc., do not have suitable spectroscopy. However, when applicable, the laser spectroscopic techniques are very powerful. 

Airborne tunable laser absorption spectrometer infrared absorption by tunable diode laser spectroscopy 41... 

A balloon-borne, open path, tunable diode laser spectrometer (21) provides a particularly elegant technique that combines the advantages of in situ and remote sampling. The radiation absorption path is defined by the laser on the balloon gondola and a retro reflector suspended up to 500 m below. Thus, a well-defined parcel of air is analyzed and the effects of sampling inlets are avoided. NO, NO , HN03, N20, and 03 have been measured simultaneously (22). 

A diode laser spectrometer. In this case, if the laser is a tunable laser, there are only two critical components the tunable laser and the detector. Typically, the enabling technology is the laser, which in this mode acts as the light source and the wavelength selection device. 

The sensitivity 7 is the derivative of the signal by the concentration (Eqs. 3.3-38, 45, 48). It should be as high as possible in order to reduce the detection limit and to enhance the precision. Ideally, a sample should give rise to a narrow line with a high peak intensity, and the spectrometer should only .see the. spectral band at which 7 is at its maximum. This is possible with spectrometers which use tunable lasers as radiation sources for absorption spectroscopy or by using spectrometers with high resolution, e.g., for trace analyses of atmo.spheric gases. 

Figure 6 (a) Absorption remote sensing apparatus. (1) Tunable laser, (2) polluted region, (3) remote retroreflector, (4) telescope, (5) detector. (b) Backscatter remote sensing apparatus. (1) Laser, (2) polluted region, (3) telescope, (4) spectrometer and detector (Reproduced by permission from Analyt. Chim. Acta, 1974, 71, 277)... 

More recently, Vogt et al. (1984 b) recorded the NN stretching band of gaseous diazomethane by means of an interferometer and a tunable diode laser spectrometer. With that equipment, the structure of the band was resolved for the first time, and nine subbands were analyzed. The recording was made with a resolution of 0.07 cm ... 

Reaction of the transition metal ions Sc", and La" (formed by laser desorption ) with C2H4 in a Fourier-transform ion cyclotron resonance (FTICR) mass spectrometer mainly yields MC2H2 + H2 . Photodissociation of MC2H2 with a tunable laser enables one to monitor the threshold for the process MC2H2 + C2H2 and thus... 

The fundamental absorption band of PH in its ground state X was observed at high resolution using a tunable diode laser spectrometer eighteen lines betwen 2224.4125 and 2107.8160 cm" (4.50 to 4.74 pm) have been identified as P-branch transitions with N" = 3 to 7 and 9, where each transition exhibits the fine-structure triplet splitting due to AJ = AN transitions between the three sublevels (J = N +1, N, N -1) of the respective rotational levels N" and N. Two further lines at 2292.1918 and 2308.1542 cm" (-4.3 pm) have been identified as the R-branch transitions with N", J " = 0,1 and 1,0. Hyperfine splitting could not be resolved. The analysis, which included rotational and centrifugal distortion effects as well as spin-spin... 

Fig. 1.62 Section of the pure rotational spectrum of 03 recorded with a high-resolution Fourier spectrometer (left spectrum) and a small section of it, measured with a tunable far-infrared laser spectrometer (right spectrum with expanded frequency scale), demonstrating the superior resolution of the laser spectrometer [201]...

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