@article{oai:repo.qst.go.jp:00080842,
 author = {Tsubochi, Masaaki and Hoshina, Hiromichi and Nagai, Masaya and Isoyama, Goro and Masaaki, Tsubouchi},
 journal = {Scientific Reports},
 month = {Oct},
 note = {We demonstrate photoacoustic wave propagation with a plane wavefront in liquid water using a terahertz (THz) laser pulse. The THz light can effectively generate the photoacoustic wave in water because of strong absorption via a stretching vibration mode of the hydrogen bonding network. The excitation of a large-area water surface irradiated by loosely focused THz light produces a plane photoacoustic wave. This is in contrast with conventional methods using absorbers or plasma generation using near-infrared laser light. The photoacoustic wave generation and plane wave propagation are observed using a system with a THz free-electron laser and shadowgraph imaging. The plane photoacoustic wave is generated by incident THz light with a small radiant exposure of <1 mJ/cm2 and delivered 600 times deeper than the penetration depth of THz light for water. The THz-light-induced plane photoacoustic wave offers great advantages to non-invasive operations for industrial and biological applications as demonstrated in our previous report (Yamazaki et al, Sci. Rep. 846295 (2020)).},
 title = {Plane photoacoustic wave generation in liquid water using irradiation of terahertz pulses},
 volume = {10},
 year = {2020}
}