Subpicosecond time-resolved infrared spectral photography

Nanosecond infrared absorption spectrometer

In the present publication, we describe the design details of a time-resolved IR absorption spectrometer with a broadband probe capability and nanosecond time resolution. The IR probe source is based on stimulated electronic Raman scattering in a metal vapor and has a measured pulsewidth of ~1 ns. Broadband collection of the IR light is facilitated by the unique use of a multielement detector array with its associated signal collection circuitry. The spectrometer has been used to record the IR spectra of some gas phase radicals which are indicative of its applicability to spectroscopic and kinetic investigations of short-lived molecular species.

Ultrashort-pulse multichannel infrared spectroscopy using broadband frequency conversion in LiIO(3)

A simple probing method for obtaining broadband multichannel infrared spectra with picosecond or higher time resolution is described. Spectrally broad infrared pulses are produced by difference frequency mixing in LiIO(3) between the second harmonic of a Nd(+3):YAG laser and the broadband output of a synchronously pumped dye laser. After sample absorption the infrared pulse is upconverted by a second LiIO(3) crystal, which yields a visible pulse that is dispersed on a multichannel vidicon detector to obtain transient spectra of 4-cm(-1) FWHM resolution.

Subpicosecond time-resolved vibrational spectroscopy by transient infrared absorption

A technique to record transient vibrational spectra with 0.5-psec resolution is reported. The apparatus is based on seeded optical parametric amplification. A study of the microscopic details of the photodissociation of carboxyhemoglobin is described as an example.

Tunable femtosecond radiation in the mid-infrared for time-resolved absorption in semiconductors

We describe the generation of 350-fs pulses tunable between 2.3 and 5.5 microm by seeded optical parametric amplification. These pulses are synchronized with visible pulses for time-resolved absorption and reflectivity in semiconductors with 500-fs resolution.

Tunable subpicosecond infrared pulse generation to 4 microm

High-power, subpicosecond infrared pulses have been generated over the wavelength region of 1.7-4.0 microm. The technique uses difference-frequency generation in a LiNbO(3) crystal. The subpicosecond output of an amplified colliding-pulse mode-locked (CPM) ring dye laser provides the two frequencies, one being the CPM fundamental, the other a portion of the subpicosecond continuum generated in an ethanol cell. Pulse width, power, and spectral characteristics are discussed.