Passively correcting phase drift in two-dimensional infrared spectroscopy.

Heterodyned two-dimensional (2D) IR spectra often suffer from inaccurate pulse delays and phase drift. We report a passive method of correcting these two inaccuracies by using wedged optics for subfemtosecond pulse delay resolution and reference measurements for phase corrections. Our approach is easy to implement into existing 2D IR spectrometers and makes experiments requiring long-term phase stability possible, such as the collection of 3D IR spectra.