Ultrafast laser pump-probe spectroscopy is an important and growing field of
physical chemistry that allows the measurement of chemical dynamics on their
natural timescales, but undergraduate laboratory courses lack examples of such
spectroscopy and the interpretation of the dynamics that occur. Here we develop
and implement an ultrafast pump-probe spectroscopy experiment for the
undergraduate physical chemistry laboratory course at the University of
California Berkeley. The goal of the experiment is to expose students to
concepts in solid-state chemistry and ultrafast spectroscopy via classic
coherent phonon dynamics principles developed by researchers over multiple
decades. The experiment utilizes a modern high-repetition rate 800 nm
femtosecond Ti:Sapphire laser, split pulses with a variable time delay, and
sensitive detection of transient reflectivity signals. The experiment involves
minimal intervention from students and is therefore easy and safe to implement
in the laboratory. Students first perform an intensity autocorrelation
measurement on the femtosecond laser pulses to obtain their temporal duration.
Then, students measure the pump-probe reflectivity of a single-crystal antimony
sample to determine the period of coherent phonon oscillations initiated by an
ultrafast pulse excitation, which is analyzed by fitting to a sine wave. Due to
the disruption of in-person instruction caused by the COVID-19 pandemic, during
those semesters students were provided the data they would have obtained during
the experiment to analyze at home. Evaluation of student written reports
reveals that the learning goals were met, and that students gained an
appreciation for the field of ultrafast laser-induced chemistry
