ELECTRIC PROPERTIES OF ORGANIC-MOLECULES - THE GROUND AND EXCITED VIBRONIC STATE DIPOLE-MOMENTS OF 1-FLUORONAPHTHALENE

The jet-cooled rotational spectrum of the A1A' <-- X1A'0(0)0 vibronic band of 1-fluoronaphthalene at 313.8 nm is recorded by scanning the fr equency-doubled output of a cw ring dye laser. Stark shifts and splitt ings of selected rotational lines are measured by applying homogenous electric fields of the order of a few kV/cm. A change from the expecte d quadratic Stark effect to a linear behaviour is observed. Diagonaliz ation of both rotational and Stark Hamiltonians is carried out with va rying dipole moment components. The best fit is achieved for mu(a) = 0 .622 (6) D, mu(b) = 1.261 (10) D, \mu\ = 1.406 (10) D in the X state a nd mu(a) = 0.519 (5) D, mu(b) = 1.283 (14) D, \mu\ = 1.384(14) D in th e A state.