Infrared laser absorption spectroscopy of the v_19aband of jet-cooled fluorobenzene

The ν19a band of fluorobenzene

“…The experimental arrangement has been described in detail before [12][13][14]. In brief, it consists on a supersonic beam system crossed by the radiation of a diode laser, which is subsequently focused on a HgCdTe detector.…”

“…The spectra of [12] included a portion near the band centre where a set of individual lines of low J and K a were resolved, plus part of the P branch, where blends of lines were found similar to those of Fig. 1.…”

“…The rotational constants of [12] provided a good starting point for the assignment of the new spectral regions. In spite of the difficulties mentioned above, we have assigned all observed lines in the spectra with a Observed minus calculated differences for J 0 ¼ 10 to 20 of the K a ¼ 4 subband in the P region.…”

“…Spin statistical weights for fluorobenzene are 5/3 for K a even/odd levels, owing to the two pairs of identical H nuclei [16]. In a former work [12], spectra of this band were recorded in the intervals 1497.0-1498.4 and 1499.2-1501.7 cm À1 , with a resolution of $0.002 cm À1 . This paper presents new measurements in the spectral regions 1502.6-1503.6 and 1503.7-1504.2 cm À1 .…”

“…Two recent papers have dealt with the microwave spectrum of fluorobenzene [9,10], giving the rotational constants and some centrifugal distortion constants of the ground [9,10] and of several vibrationally excited states [10]. The infrared fundamental bands in the 3000 cm À1 region, studied in a supersonic beam opto-acoustic set up [11], constitute the only publication of the high-resolution spectra of this species that we are aware of, besides that which sets the starting ground for the present investigation [12]. In this latter work, a portion of the spectrum of the m 19a band was recorded from a jet expansion at a rotational temperature of ca.…”