Eur. Phys. J. D 8, 385-393 (2000)
https://doi.org/10.1007/s10053-000-8810-4

Nuclear quadrupole hyperfine quantum beats in HCl and pyrimidine measured by the pump-probe method using REMPI/LIF detection

Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland

Received: 26 July 1999
Revised: 22 September 1999
Published online: 13 August 2013

Abstract

Coherent time resolved IR-UV double resonance spectroscopy with REMPI and/or LIF detection has been used to measure the nuclear hyperfine structure of a diatomic and a polyatomic molecule. The pump-probe technique was applied and the experimental set up was optimized to achieve highest spectral resolution. Following excitation of the HCl fundamental vibrational transition by a nanosecond IR laser pulse, the nuclear quadrupole coupling constants were determined to be MHz for H³⁵Cl and MHz for H³⁷Cl in the J=1 and J=2 states of the v=1 level. Nuclear (Cl) spin-rotation interaction was shown to be active with the corresponding coupling constant being MHz for H³⁵Cl and MHz for H³⁷Cl. For pyrimidine a C-H stretch vibration was excited and the quadrupole tensor elements for the rovibronic states and 1₀₁ of the level were found to be MHz, MHz and MHz. In this case the residual frequency error was reduced to 8 kHz. The results of these jet experiments independently confirm those from millimeter wave and microwave measurements on static gas samples.