Evaluation of the Laser Excitation Efficiency of B²Σ⁺ – X²Π Transition of Phosphorus Oxide

The article presents the results of calculation of vibrational and rotational terms of X²Π and B²Σ⁺ electronic states of phosphorus oxide (PO) molecule. The absorption spectrum corresponding to electronic transition B²Σ⁺ ( \({v}{\kern 1pt} '\) = 0) – X²Π ( \({v}{\kern 1pt} ''\) = 0) is calculated. The efficiency of laser excitation of PO molecules is estimated depending on the spectral parameters of radiation. It is established that the efficiency of excitation of the electronic transition B²Σ⁺ ( \({v}{\kern 1pt} '\) = 0) – X²Π ( \({v}{\kern 1pt} ''\) = 0) of PO molecule is approximately an order of magnitude lower than that of A²Σ⁺ ( \({v}{\kern 1pt} '\) = 0) – X ²Π ( \({v}{\kern 1pt} ''\) = 0) transition. The results are of practical importance from the point of view of choosing the optimal scheme for laser excitation of fluorescence of PO fragments in remote detection of organophosphates.