title: Formation of coherent rotational wavepackets in small molecule-helium clusters using impulsive alignment.
abstract: We show that rotational line spectra of molecular clusters with near zero permanent dipole moments can be observed using impulsive alignment. Aligned rotational wavepackets were generated by non-resonant interaction with intense femtosecond laser pump pulses and then probed using Coulomb explosion by a second, time-delayed femtosecond laser pulse. By means of a Fourier transform a rich spectrum of rotational eigenstates was derived. For the smallest cluster, C(2)H(2)-He, we were able to establish essentially all rotational eigenstates up to the dissociation threshold on the basis of theoretical level predictions. The C(2)H(2)-He complex is found to exhibit distinct features of large amplitude motion and very early onset of free internal rotor energy level structure.
authors.affiliation: University of Leicester, Department of Physics & Astronomy, Leicester, LE1 7RH, UK. kvh6@le.ac.uk.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Galinis
authors.forename: Luis G
authors.initials: LG
authors.lastname: Mendoza Luna
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Watkins
authors.forename: Andrew M
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authors.lastname: Ellis
authors.forename: Russell S
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authors.lastname: Minns
authors.forename: Mirjana
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authors.lastname: Mladenović
authors.forename: Marius
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authors.lastname: Lewerenz
authors.forename: Richard T
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authors.lastname: Chapman
authors.forename: I C Edmond
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authors.forename: Cephise
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authors.lastname: Cacho
authors.forename: Emma
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authors.lastname: Springate
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authors.lastname: Kazak
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authors.lastname: Göde
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authors.lastname: Irsig
authors.forename: Slawomir
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authors.lastname: Skruszewicz
authors.forename: Josef
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authors.lastname: Tiggesbäumker
authors.forename: Karl-Heinz
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authors.lastname: Meiwes-Broer
authors.forename: Arnaud
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authors.lastname: Rouzée
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Underwood
authors.forename: Marco
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authors.lastname: Siano
authors.forename: Klaus
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authors.lastname: von Haeften