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Taming Molecular Collisions

Event Details

Event Dates: 

Tuesday, February 9, 2016 - 4:00pm

Seminar Location: 

  • JILA X317

Speaker Name(s): 

Bas van de Meerakker

Speaker Affiliation(s): 

Radboud University Nijmegen, The Netherlands
Seminar Type/Subject

Scientific Seminar Type: 

  • JILA Public Seminar

Event Details & Abstract: 

Reception in JILA Hbar at 3:30.

Abstract:

The study of molecular collisions with the highest possible detail has been an important research theme in physical chemistry for decades. The level of detail that can be reached in these experiments critically depends on how well the molecules are prepared before the collision, and how well they are detected afterwards.

Over the last years we have developed methods to get improved control over molecules in a molecular beam [1]. With the Stark decelerator, a part of a molecular beam can be selected to produce bunches of molecules with a computer-controlled velocity and with very narrow velocity spreads. In addition, the molecular packets that emerge from the decelerator have small spatial and angular spreads, and have almost perfect quantum state purity. These tamed molecular beams allow for crossed beam scattering experiments with unprecedented levels of precision and sensitivity [2,3].

I will discuss our most recent results on the combination of Stark deceleration and the velocity map imaging technique to record differential cross sections. The narrow velocity spread of Stark-decelerated beams results in scattering images with an unprecedented sharpness and angular resolution. This has facilitated the observation of diffraction oscillations in differential cross sections for NO-Ar collisions [4,5], as well as the measurements of partial wave resonances at low collision energies [6].

[1] S.Y.T. van de Meerakker, H.L. Bethlem, G. Meijer, Nature Physics 4, 595 (2008).

[2] J.J. Gilijamse, S. Hoekstra, S.Y.T. van de Meerakker, G.C. Groenenboom, G. Meijer, Science 313, 1617 (2006).

[3] M. Kirste, X. Wang, H.C. Schewe, G. Meijer, K. Liu, A. van der Avoird, L.M.C. Janssen, K.B. Gubbels, G.C. Groenenboom, S.Y.T. van de Meerakker, Science 338, 1060 (2012).

[4] A. von Zastrow, J. Onvlee, S.N. Vogels, G.C. Groenenboom, A. van der Avoird, S.Y.T. van de Meerakker, Nature Chemistry 6, 216 (2014).

[5] S.N. Vogels, J. Onvlee, A. von Zastrow, G.C. Groenenboom, A. van der Avoird, S.Y.T. van de Meerakker, Phys. Rev. Lett. 113, 263202 (2014).

[6] S.N. Vogels, J. Onvlee, S. Chefdeville, A. van der Avoird, G.C. Groenenboom and S.Y.T. van de Meerakker, Science 350, 787 (2015).