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

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

“…Figure 1 displays a spectrum of the Q(1) line. All line measurements were performed as a function of laser power density in the focal region, similarly to the previous study of 12 C 18 O [17]. Figure 2 shows the AC-Stark extrapolation curves for four selected lines.…”

“…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.…”

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

“…The detection of CO and determination of its local density and temperature are essential for modelling the beginning of stellar evolution, the dynamics of interstellar clouds and nebulae, the atmospheres of planets and exoplanets, the characterisation of extra-galactic clouds, and the search for varying fundamental constants in the early Uni-Janji ć et al [24] ; and the K ępa-Rytel system (E 1 -A 1 ) by K ępa et al [25] and K ępa [20] . The other band systems investigated for the 12 C 18 O isotopologue are: 4 th Positive (A 1 -X 1 + ) [22,[26][27][28][29] ; Hopfield-Birge (B 1 + -X 1 + ) [22,27,[30][31][32][33] , C 1 + -X 1 + [27, [31][32][33][34][35] , E 1 -X 1 + [26,[31][32][33]36] , and C 1 + -B 1 + [37] .…”

“…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 . Previous deperturbation analyses of A 1 levels in 12 C 18 O, the isotopologue of present interest, were carried out by Haridass et al [26] for the v = 1 and 2 vibrational levels based on A -X bands obtained with a 10.6 m vacuum grating spectrograph to an accuracy of 0.1 cm −1 ; Beaty et al [28] for the A( v = 0 -9) levels based on the A -X spectra with accuracy of 0.2 cm −1 recorded in a supersonic jet expansion experiment; and Trivikram et al [22] for the A( v = 0) level with an accuracy of 0.001 -0.005 cm −1 using the three complementary techniques mentioned above. Thus, while a highly accurate deperturbation analysis exists for A( v = 0) in 12 C 18 O [22] , this class of analysis has not been made for higher vibrational levels.…”

“…Previous deperturbation analyses of A 1 levels in 12 C 18 O, the isotopologue of present interest, were carried out by Haridass et al [26] for the v = 1 and 2 vibrational levels based on A -X bands obtained with a 10.6 m vacuum grating spectrograph to an accuracy of 0.1 cm −1 ; Beaty et al [28] for the A( v = 0 -9) levels based on the A -X spectra with accuracy of 0.2 cm −1 recorded in a supersonic jet expansion experiment; and Trivikram et al [22] for the A( v = 0) level with an accuracy of 0.001 -0.005 cm −1 using the three complementary techniques mentioned above. Thus, while a highly accurate deperturbation analysis exists for A( v = 0) in 12 C 18 O [22] , this class of analysis has not been made for higher vibrational levels.…”