Lasers infrared tunable diode

Kanamori et al. (17) and Wood et al. (18) have reported on the use of infrared tunable diode lasers to detect by absorption the SO and CO2 photochemical fragments respectively. 

From the above considerations, it follows that C02-HI will most probably be inertially T-shaped, with at least as large a hydrogen zero point amplitude as for the case of C02-HBr. There is no fundamental reason why the structure of this complex has not yet been measured. We attempted this once by using high resolution infrared tunable diode laser spectroscopy and confirmed the inertially T-shaped character (Lin et al. n.d). However, before accurate rotational constants could be obtained, the HI ruined the vacuum pump, as it is prone to do. This lessened our appetite for a more precise structural determination. 

Nelson D. D., Zahniser M. S., McManus J. B., Shorter J. H., Wormhoudt J. C., Kolb C. E., Recent Improvements in atmospheric trace gas monitoring using mid-infrared tunable diode lasers, SPIE Proc., 2834, 148-159, 1996. 

Optical-microwave double resonance (OMDR) can considerably improve the situation and extends the advantages of microwave spectroscopy to excited vibrational or electronic states, because selected levels in these states can be populated by optical pumping. Generally dye lasers or tunable diode lasers are used for optical pumping. However, even fixed frequency lasers can often be used. Many lines of intense infrared lasers (for example, CO2, N2O, CO, HF, and DF lasers) coincide with rotational-vibrational transitions of polyatomic molecules. Even for lines that are only close to molecular transitions the molecular lines may be tuned into resonance by external magnetic or electric fields (Sect. 1.6). The advantages of this OMDR may be summarized as follows ... 

Figure 9 (A) Spectral stripping of components from the tunable diode laser infrared spectrum of cigarette smoke. From bottom to top ethylene, acrolein, methanol, and comparison with hydrazine. The reference spectrum is the lower of the two traces in each case. (B) Expanded view of the residual spectrum compared to that of hydrazine. (Reprinted with permission from Plunkett S, Parrish ME, Shafer KH, Nelson D, Shorter J, and Zahniser M (2001) Time-resolved analysis of cigarette combustion gases using a dual infrared tunable diode infrared laser system. Vibrational Spectroscopy 27 53-63 Elsevier.)...

Wormhoudt J. Radical and molecular product concentration measurements in CF and CH radio frequency plasmas by infrared tunable diode laser absorption. J Vae Sei Teehnol A. 1990 8 1722-5... 

Figure 9 Mid-infrared tunable diode laser spectra of CO, measured through a premixed CH4/O2 flame, at a total pressure of 20 torr, as a function of height above the burner surface. The maximum temperature calculated using two-line thermometry was 2150 K.

For the visible and near-ultraviolet portions of the spectmm, tunable dye lasers have commonly been used as the light source, although they are being replaced in many appHcation by tunable soHd-state lasers, eg, titanium-doped sapphire. Optical parametric oscillators are also developing as useful spectroscopic sources. In the infrared, tunable laser semiconductor diodes have been employed. The tunable diode lasers which contain lead salts have been employed for remote monitoring of poUutant species. Needs for infrared spectroscopy provide an impetus for continued development of tunable infrared lasers (see Infrared technology and RAMAN spectroscopy). 

Deguil, N., Mottay, E., Salin, F., Legros, P. and Choquet, D. (2004). Novel diode-pumped infrared tunable laser system for multi-photon microscopy. Microsc. Res. Tech. 63, 23-6. 

Krska R., Kellner R., Schiessl U., Tacke M. and Katzir, Fiber optic sensor for chlorinated hydrocarbons in water based on infrared fibers and tunable diode lasers, Appl. Phys. Lett., 1993 63 (14), 1868-1871 A. 

With respect to the considerations above, research is split into three parts. The first is connected to the kinetic description of the release of ammonia from the biomass as function of temperature. This research employs infrared spectroscopy using a tunable diode laser. Here very small biomass particles are used that are heated up very rapidly in a small reactor, which ensures that transport effects are virtually excluded from the kinetic release effects. Since ammonia is released in very small quantities it is quite hard to detect. Therefore, we first measure CO release, which is easier. In the second part we investigate the propagation of a conversion front in biomass layers. Here we perform experiments and try to establish a modeling approach for the propagation by analytical and numerical approaches. In the third part the gas-phase conversion processes are described in terms of... 

Long-path infrared absorption, using a tunable diode laser, which is claimed to have a sensitivity of 5 ppb for carbon monoxide over a 610-m path length. ... 

Other infrared absorption techniques are also used in ambient air measurements, including tunable diode laser spectroscopy (TDLS), nondispersive infrared (NDIR) spectroscopy, and matrix isolation spectroscopy. These are discussed in more detail later. 

Later chapters detail application of the present method to electron spectroscopy for chemical analysis (Chapter 5), high-resolution dispersive infrared spectroscopy (Chapter 6), and tunable-diode-laser spectroscopy (Chapter 7). Because the heart of the method is the repeated application of simple convolution, the method has been adapted to the processing of images (Kawata et al, 1978 Kawata and Ichioka, 1980a Saghri and Tescher, 1980 Maitre, 1981 Gindi, 1981). 

We conclude this chapter by presenting several examples of deconvolution of real data. Most of these examples represent deconvolutions of data that were used as part of a spectral analysis rather than generated as deconvolution examples or tests. The examples include high-resolution grating spectra, tunable-diode-laser (TDL) spectra, a Fourier transform infrared spectrum (FTIR), laser Raman spectra, and a high-resolution y-ray spectrum. 

Tunable diode laser absorption spectroscopy (TDLAS) has been used to measure oxides of nitrogen during flight (71). By tuning the laser to specific infrared absorption bands, the technique can selectively measure each compound. Detection limits are higher (25-100 pptrv for a 3-min response time) than the best chemiluminescent methods, and the instrumentation is less amenable to aircraft operations than the chemiluminescence techniques because of weight and size. 

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

Vapour pressures for a number of atmospherically relevant condensed systems have been measured with mass spectrometry. These systems include hydrates of HC1, HjS04 and HNO, supercooled liquids and pure water-ice, as well as the interactions of HC1 vapour with die solids, ice and NAT [23,47,50-55]. Vapour pressure measurements over HNOj/HjO hydrates have also been made using infrared optical absorption with light originating from a tunable diode laser [29]. This technique allowed the identification of the metastable NAD in presence of the more stable NAT under temperature and vapour pressure conditions near to those found in the polar stratosphere. Vapour pressures of Up, HN03, HC1, HBr over supercooled aqueous mixtures with sulfuric acid have been calculated using an activity model [56]. It provides a parameterized model for vapour pressures over the stratospheric relevant temperatures (185-235 K). 

Buker JF, Sample JD (1976) Tunable Diode Laser Instruments, ISA Reprint. Pittsburg, pp 76-613 Bulkin BJ (1976) Vibrational spectroscopy of liquid crystals. In Brown GH (ed) Advances in liquid crystals, vol 2. Academic, New York, p 199 Bulkin BJ (1981) Vibrational spectra of liquid crystals. In Clark RJH, Hester RE (eds) Advances in infrared and Raman spectroscopy, vol 8. Heyden, London, p 151 Bunker PR (1979) Molecular Symmetry and Spectroscopy. Academic Press, New York Bunow MR, Levin IW (1977a) Biochim Biophys Acta 464 202 Burch DE, Gryvnak DA (1967) J Chem Phys 47 4930... 

Niedziela, R.F., M.L. Norman, C.L. DeForest, R.E. Miller and D.R. Worsnop A temperature- and composition-dependent study of H2SO4 aerosol optical constants using Fourier transform and tunable diode laser infrared spectroscopy, J. Phys. Chem. A 103 (1999) 8030-8040. 

Stacknik et al, 1992), and by in-situ tunable diode laser spectrometry (May and Webster, 1989). In the 1990s, global distributions of this gas were obtained by the HALOE infrared instrument aboard UARS (Russell et al., 1993 Figure 5.59). The distribution and variability of the total column abundances of HC1 have been reported, for example, by Mankin and Coffey (1983). 

Recently, development of a more accurate and robust propane sensor by replacing the fixed-wavelength He-Ne laser with a tunable diode laser was initiated. The strongest absorption of propane in the near-infrared region occurs near 1.68 /xm. Figure 10.4 shows the first known high-resolution spectral data of propane near 1.68 /xm, from which one can identify the optimum detection strategy. In this work, the diode laser was scanned across the absorption peak at 1.6837 /xm at 500 Hz to mecisure propane concentration. This sensor was applied to the head-end of the PDE at Stanford University, as shown in Fig. 10.5. The initial results of propane measurements are shown in Fig. 10.6. These results contain a wealth of information... 

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