  We demonstrate an approach to two-dimensional electronic spectroscopy (2DES)
that combines the benefits of shot-to-shot detection at high-repetition rates
with the simplicity of a broadband white light continuum input and conventional
optical elements to generate phase-locked pump pulse pairs. We demonstrate this
through mutual synchronization between the laser repetition rate,
acousto-optical deflector (AOD), pump delay stage and the CCD line camera,
which allows rapid scanning of pump optical delay synchronously with the laser
repetition rate while the delay stage is moved at a constant velocity. The
resulting shot-to-shot detection scheme is repetition rate scalable and only
limited by the CCD line rate and the maximum stage velocity. Using this
approach, we demonstrate measurement of an averaged 2DES absorptive spectrum in
as much as 1.2 seconds of continuous sample exposure per 2D spectrum. We
achieve a signal-to-noise ratio (SNR) of 6.8 for optical densities down to 0.05
with 11.6 seconds of averaging at 100 kHz laser repetition rate. Combining
rapid scanning of mechanical delay lines with shot-to-shot detection as
demonstrated here provides a viable alternative to acousto-optic pulse shaping
(AOPS) approaches that is repetition-rate scalable, has comparable throughput
and sensitivity, and minimizes sample exposure per 2D spectrum with promising
micro-spectroscopy applications.
