MicroWave Spectroscopy Laboratory

Instruments RAD Spectrometer  Terahertz spectrum of OCS

Terahertz spectrum of OCS

Fig. 1

Fig. 2

Fig. 3

The OCS spectrum was studied in a frequency range of 24 to 859 GHz, which covers almost all the OCS rotational spectra observable at room temperature (Fig.1) and corresponds to the interval of rotational quantum numbers J from 1 to 69. High signal-to-noise ratio of spectral lines observed using the RAD spectrometer allowed not only accurate measurement of pressure broadening parameters in rotational spectrum of OSC [Fig. 2 and Ref. 1 (2009)] but also resulted in determination of speed dependence of collisional relaxation (Fig. 3). It is shown for the first time for the whole rotational spectrum that speed dependent models not only improve accuracy of modeling the observed line profiles but also give physically grounded values of collisional relaxation parameters.

For more details see Ref. 5 (2012).

Fig. 4.

J= 58 - 59 line of OCS. Residuals (amplified by 20) correspond to Voigt (a) and speed dependent (SD) Voigt (b and c) profiles. Frequency detuning is shown from 716.540 GHz.

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