Ultrafast Coulomb explosion imaging of molecules and molecular clusters

Abstract

Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging (CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation - clusters. The method is unique for identifying the atomic locations with ångstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summaries the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI (UCEI). Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.

Molecular photodissociation dynamics revealed by Coulomb explosion imaging

“…Determining the speeds and the directions of the resulting fragment ions allowed reconstruction of the parent cation structure at the instant of CE. Short (femtosecond) duration laser pulses are now increasingly being used to initiate the CE of isolated molecules, [37][38][39][40] providing new insights into the structures of molecules and small clusters, [41][42][43][44] enabling the distinction of isomers 45,46 and even enantiomers 47,48 and the preparation of exotic cations. 49 Such experiments have, for example, recently allowed real-time studies of the Jahn-Teller driven distortions of the CH 4 + cation.…”

Measuring Charge Distribution of Molecular Cations by an Atomic Coulomb Probe Microscope

“…[9][10][11][12][13] As a well-known technique, Coulomb explosion imaging (CEI) has proven to be powerful in determining structures of weakly bonded clusters, even in specific quantum states. [14][15][16] Recently, the structures for small molecules, atomic clusters, and molecular dimers have been obtained. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, only the distance between charge centers 𝑅cc of fragments can be measured, suggesting that only the structures of atomic clusters can be determined accurately since the charge centers are the same as the mass centers.…”

“…[14][15][16] Recently, the structures for small molecules, atomic clusters, and molecular dimers have been obtained. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, only the distance between charge centers 𝑅cc of fragments can be measured, suggesting that only the structures of atomic clusters can be determined accurately since the charge centers are the same as the mass centers. [14][15][16][17] In general, the charge center does not coincide with the mass center in a molecule, which makes it difficult to predict the structure of complex molecules and molecular clusters accurately.…”

“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, only the distance between charge centers 𝑅cc of fragments can be measured, suggesting that only the structures of atomic clusters can be determined accurately since the charge centers are the same as the mass centers. [14][15][16][17] In general, the charge center does not coincide with the mass center in a molecule, which makes it difficult to predict the structure of complex molecules and molecular clusters accurately. Therefore, the pre-determined charge distribution is of great significance for CEI to determine the atomic position of molecules accurately.…”

Editorial: Celebrating the 30 Wonderful Year Journey of Chinese Physics B

“…Li et al summarize determination of the three-dimensional equilibrium geometry of molecules and molecular clusters through reconstruction by fragments momenta method, and also show how dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast laserinduced Coulomb explosion imaging technique. [18] Ma et al review twenty-year studies on atomic structure and collision dynamics with highly charged ions (HCIs) based on heavy ion storage rings and electron ion beam traps, and propose some new and interesting topics for cutting-edge research employing HCIs in current and future large-scale accelerator facilities around the world. [19] He et al outline recent progress in attosecond pulse generation and attosecond spectroscopy capable of recording ultrafast movies of nuclear and electronic dynamics with unprecedented temporal and spatial resolution.…”