Emission spectra of free base phthalocyanine in superfluid helium droplets

Abstract

We report on the electronic emission spectra of free-base phthalocyanine doped into superfluid He4 droplets. The emission spectra of phthalocyanine obtained upon vibronic excitation show a doubling of all lines, absent in the gas phase [Fitch, Wharton, and Levy, J. Chem. Phys. 70, 2018 (1979)]. Similar features found for Mg-phthalocyanine in He4 droplets suggest that this doubling is due to the helium environment. Quantized relaxation states of the first helium layer surrounding the embedded molecule are discussed as likely causes of the doubling.

Electronic spectroscopy of 9,10-dichloroanthracene inside helium droplets

“…7,25,26,31,[38][39][40] Thus, the intramolecular contributions to fluorescence, r,droplet bβ , can be neglected. diss bβ may depend on the excited state bβ since the relaxation into the vibrational ground state of S 1 may compete with other processes such as relaxation into possible dark states or into the electronic ground state or long lived triplet states.…”

“…As known since long, for solid matrices vibronic excitation is followed by the dissipation of vibrational excess energy into the helium droplet prior to radiative decay. [25][26][27] The depletion method mainly applied to record the IR spectra of molecules in superfluid helium droplets is based on this mechanism. Finally, the data on 9,10-DCA in helium droplets are an interesting complement to those of bare anthracene (AN) in helium droplets.…”

Spectroscopy and dynamics in helium nanodroplets

“…In some molecules, the first vibrationally resolved electronic spectra have been recorded [195,197]. This line of work has been extended to high-resolution fluorecence emission spectroscopy by Slenczka and coworkers [198,199,200]. Molecules like tetracene, pentacene, perylene and phthalocyanines have been studied.…”

Homo- and heteronuclear alkali metal trimers formed on helium nanodroplets. Part II. Femtosecond spectroscopy and spectra assignments

“…Note that cw-spectroscopy of larger molecules embedded inside helium nanodroplets indicates that vibronic modes experience variable damping depending on their symmetry. 66 The lack of visible revival structures in Fig. 4 presumably originates from strongly anharmonic potential energy surfaces in combination with limited observation times due to dephasing.…”