Detecting chirality in mixtures using nanosecond photoelectron circular dichroism

Abstract

We report chirality detection of structural isomers in a gas phase mixture using nanosecond photoelectron circular dichroism (PECD). Combining pulsed molecular beams with high-resolution resonance enhanced multi-photon ionization (REMPI) allows...

Trends in angle-resolved molecular photoelectron spectroscopy

“…2 PECD images extracted from mixtures of camphor and fenchone, relative to the 4 combinations of R/S enantiomers, REMPI results relative to excitation at 408.8 nm and 416.6 nm wavelengths, the first resonant for camphor, the second for fenchone. 275 Signals from the two molecules can be clearly distinguished, as well as the specific R/S combination. the full PAD relative to the RCP and LCP, taking sum and difference, PAD and PEELD (Photoelectron Elliptical Dichroism) are defined, the latter showing very strong signatures of the chirality.…”

“…2 employed the same technique to provide detection of absolute configuration in a mixture of chiral molecules, in this case camphor and fenchone. 275 By tuning to the 3s intermediate state resonance, which is separated by about 8 nm (114 meV) in the two compounds, almost pure signals from each molecule could be achieved, and PECD was able to differentiate accurately among the four possible enantiomer mixtures, which may become a feasible tool for chiral analysis of mixtures.…”

“…Fig.2PECD images extracted from mixtures of camphor and fenchone, relative to the 4 combinations of R/S enantiomers, REMPI results relative to excitation at 408.8 nm and 416.6 nm wavelengths, the first resonant for camphor, the second for fenchone 275. Signals from the two molecules can be clearly distinguished, as well as the specific R/S combination.Figure reproduced from Fig.…”

Ultrafast chirality: the road to efficient chiral measurements

“…This is the essence of the first electric-dipole revolution: strong enantio-sensitive response without chiral light. It has brought a family of new methods benefiting from highlyefficient enentio-sensitive signals based on detecting electrons or photons: PECD in one-photon [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] and multi-photon regimes [52][53][54][55][56][57][58][59][60][61][62][63][64][65], PXECD and PXCD [66], three wave mixing [75,[116][117][118][119] and enantio-sensitive microwave spectroscopy [80,112]. The relevant vectorial observables are the induced polarization or photoelectron current.…”

Dual-Beam Circular Dichroism Spectroscopy of Jet-Cooled Chiral Molecules

“…In recent decades, CD spectroscopy of gas-phase molecules has attracted much attention because it can provide mass- and conformation-selective CD spectra. − Since the first CD measurement of jet-cooled 3-methylcyclopentanone, resonance-enhanced multiphoton ionization (REMPI) spectroscopy has been employed to measure the CD of gaseous molecules. ,, Photoelectron CD spectroscopy has also been used to investigate the chiroptical properties of gas-phase molecules and clusters. − Cavity ring-down polarimetry has been developed to measure the CD of chiral molecules in the gas phase . The matrix isolation technique has been employed to obtain vibrational CD spectra of chiral molecules in cryogenic rare gas matrices. , Nevertheless, obtaining CD spectra of gas-phase molecules is still challenging because of the low molecular densities and small CD values.…”