Rotational coherence spectroscopy of para-cyclohexylaniline by stimulated Raman-induced fluorescence depletion and stimulated emission pumping

摘要

A high-resolution rotational coherence spectroscopy (RCS) investigation of para-cyclohexylaniline (pCHA) was performed using the methods of time-resolved stimulated Raman-induced fluorescence depletion (TRSRFD) and time-resolved stimulated emission pumping (TRSEP). TRSRFD and TRSEP are sensitive to ground state or excited state rotational constants, respectively and allow the deconvolution of the time-resolved fluorescence depletion (TRFD) spectrum to which both ground state and excited state rotational constants contribute. Moreover, from a detailed analysis of the presented experimental data it is deduced, that photoionization and internal vibrational relaxation (IVR)—not included in the picture of TRSEP, TRSRFD and TRFD—also contribute to the RCS spectra. The obtained rotational constants are in very good agreement with our previous high-resolution TRFD investigation of pCHA, allowing additionally for the unambiguous assignment of the excited state J-type transients. From a linear regression analysis of 25 transient positions (B+ C)’ = 719.74(53) MHz was calculated, confirming set (II) of our former investigation [C. Riehn, A. Weichert, U. Lommatzsch, M. Zimmermann, and B. Brutschy, J. Chem. Phys. 112, 3650 (2000)1.