Rotational analysis of the Ångström system (B1Σ+–A1Π) in the rare 13C17O isotopologue

Abstract

Although yet unobserved in the very rare 13C17O isotopologue, the Ångström system (B1Σ+–A1Π) was obtained under high resolution as an emission spectrum using a conventional spectroscopic technique.The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total, 192 transition wave numbers belonging to two bands (0–1 and 0–2) were precisely measured and rotationally analyzed. This method allowed us to determine the merged rotational constants B0=1.8131941(58)cm−1 and D0=5.5620(46)×10−6cm−1 and the individual molecular constant B1=1.471059(47)cm−1, D1=5.315(64)×10−6cm−1, B2=1.451762(13)cm−1, D2=7.812(16)×10−6cm−1 for the as yet unanalyzed 13C17O molecule B1Σ+ and A1Π states, respectively. The band origins σ0-v″ of the Ångström system in the 13C17O molecule were also calculated.Numerous rotational perturbations observed in the A1Π state in 13C17O molecule have been identified and analyzed in detail. The suspected candidates responsible for these irregularities were indicated by means of a graph of the rovibronic levels of the neighboring states based on the estimated term value in the 13C17O molecule. The values of these perturbations have also been defined for both the e- and f-parity of the A1Π(v=1 and 2) state. Simultaneously, the B1Σ+ state was observed to be quite regular up to the observed Jmax level.