Stretching our understanding of C-3: Experimental and theoretical spectroscopy of highly excited nv(1) + mv(3) states (n = 7 and m = 3)

摘要

We present the high resolution infrared detection of fifteen highly vibrationally excited nv(1) + mv(3) combination bands (n = 7 and m = 3) of C-3 produced in a supersonically expanding propyne plasma, of which fourteen are reported for the first time. The fully resolved spectrum, around 3 mu m, is recorded using continuous wave cavity ring-down spectroscopy. A detailed analysis of the resulting spectra is provided by ro-vibrational calculations based on an accurate local ab initio potential energy surface for C-3 ((X) over tilde (1)Sigma(+)(g)). The experimental results not only offer a significant extension of the available data set, extending the observed number of quanta v(1) to 7 and v(3) to 3, but also a vital test to the fundamental understanding of this benchmark molecule. The present variational calculations give remarkable agreement compared to experimental values with typical accuracies of similar to 0.01% for the vibrational frequencies and similar to 0.001% for the rotational parameters, even for high energy levels around 10 000 cm(-1). Published by AIP Publishing.