Linewidth, lineshift, and lineshape measurements on rotational transitions of OCS using frequency modulation

Submillimeter-wave spectrum of carbonyl sulfide: rare isotopic species

“…c Present study.expression at low J , because the linewidth of the lowest few transitions suffers from Dicke effect. Therefore, the values 6.05[21], 5.92[22], and 5.78[23] MHz/Torr, which agree with other observed values and were determined by absorption spectroscopy, were used for the…”

“…In the model, the r m coordinates are fitted to Table 1 Observed and calculated transition frequencies of 18 14 13 161747.779 (16) )0.025 15 14 173299.156 (24) 0.000 16 15 184850.072(32) )0.009 17 16 196400.548 (23) )0.004 21 20 242597.303 (19) )0.010 22 21 254145.057 (18) )0.022 23 22 265692.214 (19) )0.007 24 23 277238.746 ( …”

Precise Lamb-dip measurements of millimeter and submillimeter wave rotational transitions of 16O12C32S

“…De Vreede et al [12] could not find out any noticeable pressure induced line shift at room temperature for the OCS J = 3 ‹ 2 transition within an accuracy of 6 kHz/Torr; this feature was another important argument to select the molecule for our studies. The line center determined in [12] was consistent with a previous Lamb-dip measurement by Costain [6], the discrepancy of 0.7 kHz is within experimental uncertainty.Our measurements above 200 GHz have shown discrepancies with the Lamb-dip frequencies given by Winton and Gordy [7] which are systematically shifted in the order of +5 kHz. Further there are also no sufficiently precise data available at submillimeter frequency range.…”

“…De Vreede et al [12] could not find out any noticeable pressure induced line shift at room temperature for the OCS J = 3 ‹ 2 transition within an accuracy of 6 kHz/Torr; this feature was another important argument to select the molecule for our studies. The line center determined in [12] was consistent with a previous Lamb-dip measurement by Costain [6], the discrepancy of 0.7 kHz is within experimental uncertainty.…”

“…This is about one to two orders of magnitude more accurate compared with the traditional Doppler spectroscopy (see, for example, recent work on rare OCS isotopomers [18]). The OCS rotational lines can be considered as a good secondary standard for precise laboratory measurements of frequencies so far as the uncertainties for all calculated rotational 16 O 12 C 32 S transitions in the ground vibrational state below 500 GHz do not exceed 1 kHz and no significant pressure shift was found at room temperature [12]. Table 3 Rotational constants of 16 O 12 C 32 S obtained from the fit of the line center frequencies listed in Table 2 Constant…”