ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
A high-resolution two-color spectrometer for rotational coherence spectroscopy (RCS) in the picosecond time domain has been developed and applied to several molecular systems. This time-resolved method enables the structural characterization of large molecules and clusters in the gas phase by determination of their rotational constants with high precision. Our spectrometer is based on a well stabilized solid-state chirped pulse amplified laser setup with an adjustable pulse duration in the picosecond range. Two optical parametric generators provide tunable radiation in the UV spectral range, with a pulse duration of 2 ps. An interferometric setup is employed in order to perform pump–probe experiments with up to 8 ns delay between pump and probe pulse. Two different pulse to pulse switching modes and the online monitoring of laser parameters have been integrated to enable the measurement of RCS traces with high resolution and good signal/noise ratio. These modes also permit the identification of weak features that would otherwise not have been observed. The molecular samples are prepared in a supersonic expansion and either the laser induced fluorescence or the photoion current are detected as a function of the time delay between pump and probe pulse. The performance of the spectrometer is demonstrated by recording a high-resolution RCS spectrum of para-difluorobenzene⋅argon and benzene. From their analysis the rotational constants of the ground state and electronically excited state of both species were obtained with an estimated uncertainty on the order of 10−4 and 10−5, respectively, in excellent agreement with high-resolution frequency-resolved data. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1370559
