### Atomic, Molecular, and Optical Physics Seminar

Monday, December 3, 2018
4:00pm – 5:00pm

Storrs Campus
Physics Building, P121

Dr. Thomas Allison Stony Brook University

Cavity-enhanced ultrafast spectroscopy: ultrafast meets ultrasensitive

Ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D spectroscopy, are widely used across many disciplines. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. Using a frequency comb laser and optical cavities, we present a technique for performing ultrafast optical spectroscopy with high sensitivity, enabling work in dilute gas-phase molecular beams. Resonantly enhancing the probe pulses, we demonstrate transient absorption measurements with a detection limit of $$\Delta OD = 2 \times 10^{−10}$$ ($$1 \times 10^{-9} / \sqrt{Hz}$$). Resonantly enhancing the pump pulses allows us to produce a high excitation fraction at a high repetition rate, so that signals can be recorded from samples with optical densities as low as $$OD ≈ 10^{−8}$$, or column densities $$< 10^{10}$$ molecules∕cm$$^2$$. In this talk, I will discuss initial demonstration experiments, methods for cavity-enhancing multidimensional spectroscopy signals using multiple frequency combs, and progress towards widely tunable cavity-enhanced ultrafast spectrometers operating from the ultraviolet to the infrared.

Contact:

Prof. C. Trallero

Physics Department (primary)