Ion core structure in (C(2)n+ and (CS2)n- (n=3-10) studied by infrared photodissociation spectroscopy.

Infrared photodissociation spectra of (CS(2))(n) (+) and (CS(2))(n) (-) with n=3-10 are measured in the 1100-2000 cm(-1) region. All the (CS(2))(n) (+) clusters exhibit three bands at approximately 1410, approximately 1490, and approximately 1540 cm(-1). The intensity of the 1540 cm(-1) band relative to those of the other bands increases with increasing the cluster size, indicating that the band at 1540 cm(-1) is assignable to the antisymmetric CS stretching vibration of solvent CS(2) molecules in the clusters. On the basis of density functional theory calculations, the 1410 and 1490 cm(-1) bands of (CS(2))(n) (+) are assigned to CS stretching vibrations of the C(2)S(4) (+) cation core with a C(2) form. The (CS(2))(n) (-) clusters show two bands at around 1215 and 1530 cm(-1). Similar to the case of cation clusters, the latter band is ascribed to the antisymmetric CS stretching vibration of solvent CS(2) molecules. Vibrational frequency analysis of CS(2) (-) and C(2)S(4) (-) suggests that the 1215 cm(-1) band is attributed to the antisymmetric CS stretching vibration of the CS(2) (-) anion core with a C(2v) structure.