Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 3: Novel Spectroscopies

MO 3.2: Talk

Monday, March 11, 2024, 17:15–17:30, HS 1015

Nonlinear 2D spectroscopy of single molecules — •Simon Durst, Sanchayeeta Jana, and Markus Lippitz — Universität Bayreuth

Fluorescence-detected 2D electronic spectroscopy (F-2DES) allows the measurement of ultrafast electron dynamics in complex systems while disentangling this spectral information from energetically similar phenomena, such as molecular vibration. Measuring the 2D spectra of single molecules instead of molecular ensembles should provide an even clearer picture of the underlying physics and give insight into the statistical distribution of optical properties and the environment of the molecules.

To measure these spectra we use four collinear, phase-modulated femtosecond pulses, generated by a four-arm Mach-Zehnder Interferometer to excite single molecules with a confocal microscope. Their emitted fluorescence is modulated at the mixing frequencies of the individual pulses, so we can use phase-sensitive lock-in detection to detect the nonlinear signal and separate it from linear effects. This measurement technique promises high spectral, temporal and spatial resolution.

In this talk, we present our setup and method to measure the 2D spectra of single dibenzoterrylene (DBT) molecules, which are immobilised in a PMMA matrix. We show results from these measurements and compare them with the ensemble data.

Keywords: Nonlinear Spectroscopy; 2D Spectroscopy; Single Molecules; Ultrafast Spectroscopy; Coherent Spectroscopy