TRANSIENT FREQUENCY-MODULATION DIODE LASER SPECTROSCOPY OF METHYLENE

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/19165

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 Title: TRANSIENT FREQUENCY-MODULATION DIODE LASER SPECTROSCOPY OF METHYLENE Creators: Chang, Bor-Chen; Marr, Andrew J.; Sears, Trevor J. Issue Date: 1998 Abstract: Transient frequency-modulation (FM) techniques have been combined with diode laser absorption to acquire high resolution spectra of the methylene $(CH_{2}) \tilde{b}^{1} B_{1} \leftarrow \tilde{a}^{1} A_{1}$ electronic transition in the vicinity of $10000cm^{-1}-10600cm^{-1}$. These spectra represent the first application of transient FM techniques using a simple and inexpensive diode laser source to high resolution spectroscopy. By comparison with previous data obtained using a dual-beam absorption setup, the improvement in signal-to-noise ratio is dramatic. A sensitivity $(\Delta I/I)$ for raw signals of $1.1 \times 10^{-4}$ in $0.6 \mu$sec is now routinely achieved for 0.4 mW laser power at the detector. The integrated absorption signals have even larger signal-to-noise ratios. This can be compared with the shot noise limit for absorption of $2.9 \times 10^{-5}$ for these parameters. This talk will concentrate on details of the experimental design. URI: http://hdl.handle.net/1811/19165 Other Identifiers: 1998-WH-02