Phase Dependence of Double-Resonance Experiments in Rotational Spectroscopy.
We here report on double-resonance experiments using broadband chirped pulse Fourier transform microwave spectroscopy that can facilitate spectral assignment and yield information about weak transitions with high resolution and sensitivity. Using the diastereomers menthone and isomenthone, we investigate the dependence of pumping a radio frequency transition on both the amplitude and phase of the signal from a microwave transition with which it shares a common rotational level. We observe a strong phase change when scanning the radio frequency through molecular resonance. The direction of the phase change depends on the energy level arrangement, that is, if it is progressive or regressive. The experimental results can be simulated using the three-level optical Bloch equations and described with the AC Stark effect, giving rise to an Autler-Townes splitting.
†Max-Planck-Institut für Struktur und Dynamik der Materie, Luruper Chaussee 149, D-22761 Hamburg, Germany.|‡Center for Free-Electron Laser Science, Luruper Chaussee 149, D-22761 Hamburg, Germany.
David
D
Schmitz
†Max-Planck-Institut für Struktur und Dynamik der Materie, Luruper Chaussee 149, D-22761 Hamburg, Germany.|‡Center for Free-Electron Laser Science, Luruper Chaussee 149, D-22761 Hamburg, Germany.
V Alvin
VA
Shubert
¶Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States.
David
D
Patterson
†Max-Planck-Institut für Struktur und Dynamik der Materie, Luruper Chaussee 149, D-22761 Hamburg, Germany.|‡Center for Free-Electron Laser Science, Luruper Chaussee 149, D-22761 Hamburg, Germany.
Anna
A
Krin
†Max-Planck-Institut für Struktur und Dynamik der Materie, Luruper Chaussee 149, D-22761 Hamburg, Germany.|‡Center for Free-Electron Laser Science, Luruper Chaussee 149, D-22761 Hamburg, Germany.
Melanie
M
Schnell
chirped pulse Fourier transform rotational spectroscopy; double-resonance spectroscopy; microwave spectroscopy; radio frequency