TY - JOUR
T1 - Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation
AU - Miyamoto, Yuki
AU - Hara, Hideaki
AU - Hiraki, Takahiro
AU - Masuda, Takahiko
AU - Sasao, Noboru
AU - Uetake, Satoshi
AU - Yoshimi, Akihiro
AU - Yoshimura, Koji
AU - Yoshimura, Motohiko
PY - 2018/1/14
Y1 - 2018/1/14
N2 - We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.
AB - We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.
KW - hydrogen molecule
KW - molecular vibration
KW - third-harmonic generation
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U2 - 10.1088/1361-6455/aa9782
DO - 10.1088/1361-6455/aa9782
M3 - Article
AN - SCOPUS:85038613121
VL - 51
JO - Journal of Physics B: Atomic, Molecular and Optical Physics
JF - Journal of Physics B: Atomic, Molecular and Optical Physics
SN - 0953-4075
IS - 1
M1 - 015401
ER -