DIRECT OBSERVATION OF RYDBERG{--}RYDBERG TRANSITIONS IN CALCIUM ATOMS
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Date
2010
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Publisher
Ohio State University
Abstract
Chirped Pulse millimeter-Wave (CPmmW) spectroscopy, an extension of Brooks Pate's Chirped Pulse Fourier Transform Microwave (CP-FTMW) technique, has been adapted to observe electronic transitions between Rydberg states. The feasibility of this method has been demonstrated on calcium atoms of effective principal quantum number $n^{*}$ of 40 and at frequencies of 70{--}84 GHz. Whereas Rydberg states are generally detected by ionization, we directly observe the free induction decay that they emit after polarization by the chirped pulse. Spectra with a bandwidth of 10 GHz and resolution of 1 MHz or better may be acquired in several shots, which could enable high-resolution ``pure electronic'' spectroscopy of molecules in core-nonpenetrating Rydberg states. The available millimeter-wave power is not a limitation in this experiment because the transition dipole moments are large ($\sim$5,000 Debye). Furthermore, the ability to quickly and arbitrarily polarize the sample opens avenues for optical plus millimeter-wave coherent experiments. Schemes to extend this technique to molecules are under development.
Description
Author Institution: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139