NEAR-INFRARED ELECTRONIC-TRANSITIONS OF BIN

The near-infrared spectrum of the chemiluminescence from the reaction of microwave-discharged nitrogen with bismuth vapor in a fast-flow sys tem has been investigated by high-resolution Fourier-transform spectro metry. In addition to the a3SIGMA+(a(1)1) --> X1SIGMA+(X0+) system pre viously identified in LIF studies, two new band systems of BiN have be en observed, which are assigned to the transitions b5SIGMA+(b(1)0+) -- > X1SIGMA+(X0+) and b5SIGMA+(b(1)0+) --> a3SIGMA+(a(1)1). Vibrational and rotational analyses of the bands yielded the following molecular c onstants of the X0+, a(1)1, and b(1)0+ states (in cm-1): for X0+ (upsi lon = 0-11): omega(e) = 736.570(3), omega(e)x(e) = 4.829(1), omega(e)y (e) = -0.0187(2), omega(e)Z(e) = -0.000403(5), B(e) = 0.343100(2), alp ha(B) = -2.526(2)E - 3, beta(B) = -1.29(3)E - 5, gamma(B) = -5.4(2)E - 7, D(e) = 2.984(3)E - 7, alpha(D) = 3.3(1)E - 9, beta(D) = 1.8(1)E - 10; for a(1)1 (upsilon = 0-2), T(e) = 10144.625, omega(e) = 501.647, o mega(e)X(e) = 4.684, B(e) = 0.283773, alpha(B) = -2.86E - 3, beta(B) = -1.7E - 5, D(e) = 3.653E - 7, alpha(D) = 6.6E - 9, q(e) approximately q(v) = 1.168E - 4, q(De) approximately q(Dv) = 1.15E - 9; for b10+ (u psilon = 0), T0 = 16242.569, Delta(G)1/2 = 314.723, Delta(G)3/2 = 294. 998, Delta(G)5/2 = 283.033, B0 = 0.251085(1), D0 = 6.69E - 7, H0 = 5.0 7E - 12, where the numbers in parentheses give the standard deviations of the parameters in units of the last digit. The vibrational levels upsilon = 1, 2, and 3 of b(1)0+ are perturbed. From the OMEGA-doubling constant q(e) and the rotational constant B(e) of state a(1)1, the sp in-spin splitting of a3SIGMA+ is estimated to be almost-equal-to 2720 cm-1. Weak magnetic hyperfine splitting of the rotational levels of a( 1)1 shows up by line broadening of low-J lines in the a1 --> X and b1 --> a1 bands. (C) 1994 Academic Press, Inc.