Knowledge Bank

Fully resolved rotational structure of the $8¯01$ vibronic bands of the $A1B1u\leftarrow X1Ag$ electronic transition of naphthalene have been investigated in the $32444-32458cm-1$ region with the techniques of Doppler-free laser polarization (DFLP) spectroscopy and optical-optical double resonance (OODR). For the first time Doppler-free polarisation labeling spectroscopy is successfully applied to a large polatomic molecule and it is demonstrated to be very efeective when combined with OODR. A typical linewidth of 12 MHz was observed, limited only by residual Doppler broadening. By exploiting Doppler-free optical-optical double resonance polarization (DFOOPL) spectroscopy, a combination of DFLP and OODR, both V-type and A-type transition were observed and thereby facilitates the unambiguous assignment of the observed lines. The wave numbers of these lines were recorded with an accuracy better than $0.0002cm-1$. The assignments of the observed transitions, spectroscopic analysis and dynamics will be discussed.