Spectroscopy and perturbation analysis of the A¹π (v=0) state of ¹³ C¹⁶ O

Abstract

The lowest v = 0 level of the A 1 state of the 13 C 16 O isotopologue of carbon monoxide has been reinvestigated with a variety of high-resolution spectroscopic techniques. The A 1 −X 1 + (0, 0) band has been studied by vacuum-ultraviolet Fourier-transform absorption spectroscopy, using the SOLEIL synchrotron as a radiation source. Spectra were obtained under quasi-static gas conditions at liquidnitrogen temperature, room temperature and at an elevated temperature of 900 K, with absolute accuracies of 0.01−0.03 cm −1 . Two-photon Doppler-free laser spectroscopy has been applied to a limited number of transitions in the A 1 −X 1 + (0, 0) band, under collision-free circumstances of a molecular beam, yielding an absolute accuracy of 0.002 cm −1 . The third technique is high-resolution Fourier-transform emission spectroscopy in the visible region applied to the B 1 + −A 1 (0, 0) band in a gas discharge, at an absolute accuracy of up to 0.003 cm −1 . With these methods, rotational levels of A 1 (0) could be studied in both parity components up to a rotational quantum number of J = 46. The frequencies of 397 transitions were used to analyse the perturbations between the A 1 (0) level by vibrational levels of the D 1 , e 3 − , d 3 , and a 3 + states.

Perturbations in the A1Π,v= 0 state of12C18O investigated via complementary spectroscopic techniques

“…The discharge glow was focused by a plano-convex quartz lens onto the entrance aperture (1.0 mm diameter) of a 1.71 m Fourier-transform (FT) spectrometer [28,30]. A recent modification of this spectrometer significantly reduced the reflection of the HeNe laser beam, used for calibration and control of the position of a movable retroreflecting mirror, from optical elements in the interferometer and detector compartments, and noticeably improved its sensitivity in the VIS and UV regions.…”

“…The general methodology of this work is similar to our recent studies of other CO isotopologues [28][29][30]. Three spectroscopic techniques are employed: Doppler-free two-photon laser spectroscopy of the A The first technique provides transition frequencies with ultrahigh accuracy and the latter two provide highresolution broadband measurements.…”

High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A1Π(v = 1) level in 12C18O

“…about 300 K [46][47][48] . Spectra of 12 C 18 O were obtained by coupling the emission from the hollow-cathode region unto a 1.71 m Bruker spectrometer (IFS 125-HR) working under vacuum conditions, and installed at the University of Rzeszów [42,49] . The final spectrum was produced after acquiring 128 FT-scans conducted with an instrumental resolution of 0.018 cm −1 .…”

“…Recently, the A 1 electronic state in 12 C 16 O was accurately re-examined using two experimental techniques: twophoton Doppler-free laser spectroscopy with 0.002 cm −1 accuracy and synchrotron based Fourier-transform (VUV-FT) spectroscopy with an accuracy as good as 0.01 cm −1 [40,41] . Deperturbation analyses of the A 1 state in other isotopologues have been conducted as well: Niu et al [42] for 13 C 16 O A( v = 0), Hakalla et al [43] for 12 C 17 O A( v = 1 -5), Hakalla et al [44] for 13 C 17 O A( v = 0 -3) and Hakalla et al [45] for 13 C 18 O A( v = 0). These analyses were carried out on the basis of experimental spectra obtained by three complementary techniques: FT emission spectroscopy in the VIS range with an accuracy of about 0.005 cm −1 , VUV-FT absorption spectroscopy based on synchrotron radiation with accuracy of about 0.02 cm −1 and two-photon Doppler-free laser spectroscopy with accuracy up to 0.003 cm −1 .…”

Precision spectroscopy and comprehensive analysis of perturbations in the A1∏(v= 0) state of13C18O

“…One of the aims of pursuing a precision study of the A 1 Π state was the derivation of sensitivity coefficients for probing a possible variation of fundamental constants based on the A 1 Π − X 1 Σ + system of CO [13]. Thereafter, precision studies of the A 1 Π − X 1 Σ + (0, 0) bands and the perturbing states were performed for 12 C 16 O [14], for 13 C 16 O [15], for 13 C 17 O [16], and for 12 C 18 O [17]. Here we extend these studies on the 13 C 18 O isotopologue using laserbased excitation and VUV-Fourier-transform (FT-VUV) absorption spectroscopy as well as visible Fourier-transform (FT-VIS) emission spectroscopy to observe and assign the perturbations in the A 1 Π(v = 0) state.…”