Vibrationally resolved electronic spectroscopy of rhodamine B cation at less than 5 K: combining gas phase absorption and matrix isolation fluorescence spectroscopy

Abstract

Helium tagging photodissociation action spectroscopy in the gas phase together with laser-induced fluorescence (LIF) spectroscopy in neon matrix has been used to probe the photophysics of electrosprayed rhodamine B cation cooled to < 5 K and studied in two different minimally perturbing environments ([RhB•He]⁺ as well as [RhB]⁺ in solid neon). Helium tagging experiments were performed using a newly developed apparatus He-TAG. LIF measurements were carried out using an improved matrix-isolation spectroscopy machine Depo-II. The resulting, partially vibrationally resolved electronic spectra of the S₀→S₁, resp. S₁→S₀ transition provide benchmarks for gauging the theoretical description of this prototypical organic dye. As a first approach, we have compared our spectra to TD-DFT-based predictions of vibronic structure at the Franck-Condon (FC) and Franck-Condon Herzberg-Teller (FCHT) levels.

Depletion action and fluorescence spectroscopy of rhodamine B cation at < 5 K

GRAPHICAL ABSTRACT

KEYWORDS:

• Helium tagging
• laser-induced fluorescence
• photodissociation
• matrix isolation
• electrospray ionisation

Acknowledgements

All IPC@KIT coauthors greatly appreciate the work and engagement of the mechanical and electronics workshops in helping to build He-TAG and modify Depo-II: Dieter Waltz, Torsten Franzke, Peter Fischer, Eric Fuhrmann, Martin Segner, Holger Halberstadt and Klaus Stree. In addition, we thank Aleksandr Pereverzev (Radboud University) for providing technical documentation and information about the ISORI setup. We also thank our KIT colleagues Patrick Weis and Artur Böttcher for much valuable advice in trouble-shooting during transition of He-TAG and Depo-II from testing to routine production stages. Finally, we would like to take this opportunity to acknowledge our good friend, the late Dieter Gerlich – without his encyclopedic knowledge, his professional help in many situations and his indominatable enthusiasm He-TAG would never have been built.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

MK thanks Karlsruhe Institute of Technology, Land Baden-Württemberg and DFG for financial support in constructing He-TAG and Depo-II machines. He also thanks DFG for funding the Depo-II measurements reported here [grant number KA 972/11-1]. KH acknowledges provision of computational resources by the state of Baden-Württemberg through bwHPC and the German Research Foundation (DFG) [grant number INST 40/575-1 FUGG (JUSTUS 2 cluster)].