Directions of transition dipole moments of t-butyl nitrite obtained via orientation with a strong, uniform electric field

A strong, uniform electric field was used to orient supersonically cooled t -butyl nitrite for measurements of directions of transition dipole moments. The oriented sample was dissociated with linearly polarized light, and the NO fragments were studied by (1 + 1) REMPI through the A (2)Sigma(+) state . At photolysis wavelengths of 365.8 and 351.8 nm, there was a 47% enhancem ent in the NO signal when the photolysis beam was polarized perpendicular t o the orientation field, implying a perpendicular relationship between the transition dipole of the S-1 state and the permanent dipole. Photodissociat ion at 250 and 224 nm showed the opposite trend, with a 46% enhancement in the NO signal when the photolysis beam was polarized parallel to the orient ation field. The transition dipole of the S-2 state was therefore determine d to be parallel to the permanent dipole. This experiment demonstrates the application of brute force orientation for obtaining directions of transiti on dipole moments. (C) 2000 American Institute of Physics. [S0021-9606(00)0 0323-8].