Rotationally Resolved Electronic Spectra of 1-Methoxynaphthalene in the Gas Phase

Rotationally resolved fluorescence excitation spectra of the 0 band of the S 0 1←S0 transition of 1-methoxynaphthalene have been observed using a high resolution laser spectrometer operating in the ultraviolet. The trans-1-methoxynaphthalene band is an ab hybrid band with 38% a-type character and 62% b-type character. The band origin is at 31671.7 cm, and the rotational constants are A" = 1643.98, B" = 832.62 and, C" = 554.83 MHz in the ground state, and A' = 1626.6, B' = 818.5, and C'= 546.6 MHz in the excited state. Two other bands at +16 and –70 cm from the origin band of trans-1-methoxynaphthalene exhibit a band head shape. The possibility of a perpendicular conformer as being the source of these bands is discussed.