title: Time-domain spectroscopy in the mid-infrared.
abstract: When coupled to characteristic, fingerprint vibrational and rotational motions of molecules, an electromagnetic field with an appropriate frequency and waveform offers a highly sensitive, highly informative probe, enabling chemically specific studies on a broad class of systems in physics, chemistry, biology, geosciences, and medicine. The frequencies of these signature molecular modes, however, lie in a region where accurate spectroscopic measurements are extremely difficult because of the lack of efficient detectors and spectrometers. Here, we show that, with a combination of advanced ultrafast technologies and nonlinear-optical waveform characterization, time-domain techniques can be advantageously extended to the metrology of fundamental molecular motions in the mid-infrared. In our scheme, the spectral modulation of ultrashort mid-infrared pulses, induced by rovibrational motions of molecules, gives rise to interfering coherent dark waveforms in the time domain. These high-visibility interference patterns can be read out by cross-correlation frequency-resolved gating of the field in the visible generated through ultrabroadband four-wave mixing in a gas phase.
authors.affiliation: 1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Lanin
authors.affiliation: 1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Voronin
authors.affiliation: 1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia.
authors.forename: A B
authors.initials: AB
authors.lastname: Fedotov
authors.affiliation: 1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia [3] Department of Physics and Astronomy, Texas A&M University, College Station TX 77843, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Zheltikov