The microwave spectrum and structure of tricarbon monoxide

Accurate rest frequencies for the submillimetre-wave lines of C$_{\sf 3}$O in ground and vibrationally excited states below 400 cm$^{\sf -1}$

“…We measured 37 new rotational transitions in the frequency range 307-740 GHz spanning J values from 31 to 76. Brown et al (1985); c from Klebsch et al (1985); d mean value of the measurement of Klebsch et al (1985) and the present work. Figure 3 presents the recording of the J = 71-70 transition at 682 GHz.…”

“…In previous laboratory investigations the C 3 O molecule was produced either by glow discharge of carbon suboxide, C 3 O 2 , (Tang et al 1985) or by pyrolytic processes, employing various stable precursors (Brown et al 1983;Klebsch et al 1985;Brown et al 1985;McNaughton et al 1991). In the present investigation we found it convenient to produce C 3 O by flow-pyrolysis of fumaryl chloride (Aldrich), using the same apparatus already employed to generate HC 5 N (Yamada et al 2004) and HC 7 N (Bizzocchi & Degli Esposti 2004).…”

“…These new frequencies were analysed through Eq. (1) (with l 5 = 0) including in the data set all the previously available data (Brown et al 1983(Brown et al , 1985Tang et al 1985;Klebsch et al 1985) with equal weighting. The complete list of the transition frequencies analysed and of the corresponding least-squares residuals are reported in Table 1.…”

“…In the laboratory, C 3 O has been the subject of various spectroscopic investigations: after the first identification of its centimetre-wave (cm-wave) spectrum (Brown et al 1983), the same authors performed a detailed microwave study on isotopic species, leading to a structure determination (Brown et al 1985). Later, its ground-state millimetre-wave (mm-wave) spectrum was also recorded (Tang et al 1985;Klebsch et al 1985), and a high-resolution infrared study of the ν 1 and some associated hot bands has been performed using Fourier transform infrared spectroscopy (FTIR) (McNaughton et al 1991).…”

“…Few low-J rotational lines of the v 5 = 1 bending state were recorded by Brown et al (1985), while for the v 5 = 2 and v 5 = 3 overtone states the only available spectroscopic data are those derived from the rovibrational bandby-band analysis of the ν 1 hot band system (McNaughton et al 1991). The ν 5 bending mode of C 3 O has an energy of 114 cm −1 (Hochlaf 2001), thus the first members of its vibrational ladder might be populated by the radiative pumping mechanism occurring in IRC+10216, which is one of the brightest objects of Article published by EDP Sciences the infrared sky.…”