Examples for Doppler-Limited Absorption Spectroscopy with Lasers

5 Examples for Doppler-Limited Absorption Spectroscopy with Lasers 

In Chap.7 we briefly presented the basic principles of different tunable coherent sources. This section illustrates their applications to Doppler-limited absorption spectroscopy performed either with conventional absorption measurements or based on one of the sensitive detection methods discussed above. Only 

In this spectral range it is up to now the semiconductor diode laser which has been mostly used for high-resolution laser spectroscopy. After HINKLEY [8.37] had first demonstrated in 1970 the superiority of laser spectroscopy over conventional techniques by a high-resolution absorption spectrum of SFg around 10 ym obtained with a Pb-Sn-Te laser, spectra of numerous molecules have been measured with different diode lasers. A review of the literature up to 1975 can be found in the article by HINKLEY et al. [8.38], more recent examples in [8.39] and [8.39a]. 

Coherent sources which are based on difference frequency generation (see Sect.7.2) have proved to be very successful in high-resolution infrared spectroscopy. One example is the differenoe frequency spectrometer developed by PINE [8.42,43], where the outputs from a single-mode argon laser and from a tunable single-mode cw dye laser are mixed in a LiNbO crystal (see Sect. 

The difference frequency radiation with output powers of a few liW at 

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