UV Laser Spectroscopy Using the Velocity-Modulation Technique: New Hot Bands of the B(2)Sigma(+)(u)-X(2)Sigma(+)(g) System of N(+)(2).

The laser absorption spectroscopy of molecular ions using the velocity-modulation technique has been employed in the UV region. The absorption source was a cw single-mode laser beam from an extra-cavity frequency doubling unit associated with a dye laser. The high-resolution spectrum of the First Negative system B(2)Sigma(+)(u)-X(2)Sigma(+)(g) of N(+)(2) has been studied. The N(+)(2) ions were produced with an electric discharge in a flowing gas mixture of He/N(2). Seven vibrational bands of the Deltav = 2 sequence (v' = 2-8) have been observed in the region between 30 000 and 30 600 cm(-1), and five of them for the first time at high resolution (v' = 2-4, 6, 7). A set of 770 lines have been assigned; among them are several extra - lines belonging to the A(2)Pi(u)-X(2)Sigma(+)(g) system. A standard model has been used to consider the perturbations between the rovibrational levels of the B(2)Sigma(+)(u) and A(2)Pi(u) states. An improved set of deperturbed constants and effective interaction parameters were derived for the v(B) = 3-v(A) = 14 and v(B) = 7-v(A) = 20 complexes. Copyright 1999 Academic Press.