title: Intense two-cycle laser pulses induce time-dependent bond hardening in a polyatomic molecule.
abstract: A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectrometry, symmetrical molecules such as TMS do not exhibit a prominent molecular ion (TMS(+)) as unimolecular dissociation into [Si(CH(3))(3)](+) proceeds very fast. Under a strong field and few-cycle conditions, this dissociation channel is defeated by time-dependent bond hardening: a field-induced potential well is created in the TMS(+) potential energy curve that effectively traps a wave packet. The time dependence of this bond-hardening process is verified using longer-duration (≥100 fs) pulses; the relatively slower falloff of optical field in such pulses allows the initially trapped wave packet to leak out, thereby rendering TMS(+) unstable once again.
authors.affiliation: Tata Institute of Fundamental Research, Mumbai, India.
authors.forename: K
authors.initials: K
authors.lastname: Dota
authors.forename: M
authors.initials: M
authors.lastname: Garg
authors.forename: A K
authors.initials: AK
authors.lastname: Tiwari
authors.forename: J A
authors.initials: JA
authors.lastname: Dharmadhikari
authors.forename: A K
authors.initials: AK
authors.lastname: Dharmadhikari
authors.forename: D
authors.initials: D
authors.lastname: Mathur