Stark hole-burning spectroscopy of free base isobacteriochlorin in polyvinylbutyral at 1.7 K

Abstract

Holographically detected photochemical hole-burning and the Stark effect have been employed to study free base isobacteriochlorin (2,3,7,8-tetrahydroporphin) in a polyvinylbutyral film. At 1.7 K, an upper limit for the homogeneous line width the photochemical hole was found to be 550 MHz. The shape of the hole as a function of the electric field strength was subsequently used to determine the value for the change in dipole moment (1.2 D) associated with the origin of AC tautomer's S 1←S 0 (ππ ∗) transition, which is centered at 578 nm. The angle between the change in dipole moment vector and the transition moment vector was determined to be about 40°. Also, the zero phonon contribution to the S 1←S 0 absorption band was measured as a function of wavelength at 1.7 K. The results obtained for isobacteriochlorin are compared with those of other chromophores.