Ultrafast imaging of spontaneous symmetry breaking in a photoionized molecular system
Min Li, Ming Zhang, Oriol Vendrell, Zhenning Guo, Qian-Ru Zhu, Xiang Gao, Lushuai Cao, Keyu Guo, Qin-Qin Su, Wei Cao, Siqiang Luo, Jiaqing Yan, Yueming Zhou, Yunquan Liu, Zheng Li, Peixiang Lu
Abstract
Abstract The Jahn-Teller effect is an essential mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to directly image the onset of Jahn-Teller symmetry breaking remains unreached. Here we employ ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution and unambiguously image the ultrafast dynamics of Jahn-Teller deformations of $${{\rm{CH}}}_{4}^{+}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mi>CH</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> cation in symmetry space. It is unraveled that the Jahn-Teller deformation from C 3v to C 2v geometries takes a characteristic time of 20 ± 7 fs for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C 2v structure involving complex revival process of multiple vibrational pathways of the $${{\rm{CH}}}_{4}^{+}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mi>CH</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> cation.