Intermolecular motion in strong infrared laser fields

The effect of a strong infrared laser field on the collision between two rare gas atoms is examined as a model of intermolecular motion under such conditions. After examination of the classical collision dynamics, three novel classes of collisions are identified, all of which result from interaction with the angular potential well. The signatures of these "collision mechanisms" in the classical deflection function and differential cross-section are determined. The generality of the results and the feasibility of using a modified crossed molecular beam experiment to observe these laser-induced effects are discussed

Metastable triply charged diatomic molecules produced with femtosecond pulses

We show that ultrashort pulse strong field multiphoton ionization efficiently produces metastable highly charged molecules such as metastable diatomic trications I\u2082\ub3\u207a, Br\u2082\ub3\u207a, and Cl\u2082\ub3\u207a. The efficiency of stable trication production decreases rapidly with increasing pulse duration. Weak pre- or post-pulse irradiation also prevents efficient production or survival of trications. We propose strong-field femtosecond Raman spectroscopy to determine trication vibrational frequencies.Peer reviewed: YesNRC publication: Ye

Dynamic subunit turnover in ESCRT-III assemblies is regulated by Vps4 to mediate membrane remodelling during cytokinesis

International audienceThe endosomal sorting complex required for transport (ESCRT)-III mediates membrane fission in fundamental cellular processes, including cytokinesis. ESCRT-III is thought to form persistent filaments that over time increase their curvature to constrict membranes. Unexpectedly, we found that ESCRT-III at the midbody of human cells rapidly turns over subunits with cytoplasmic pools while gradually forming larger assemblies. ESCRT-III turnover depended on the ATPase VPS4, which accumulated at the midbody simultaneously with ESCRT-III subunits, and was required for assembly of functional ESCRT-III structures. In vitro, the Vps2/Vps24 subunits of ESCRT-III formed side-by-side filaments with Snf7 and inhibited further polymerization, but the growth inhibition was alleviated by the addition of Vps4 and ATP. High-speed atomic force microscopy further revealed highly dynamic arrays of growing and shrinking ESCRT-III spirals in the presence of Vps4. Continuous ESCRT-III remodelling by subunit turnover might facilitate shape adaptions to variable membrane geometries, with broad implications for diverse cellular processes