Related Experiment Video
Updated: Aug 5, 2026

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Quantum Chemistry Calculations and Spectroscopic Predictions of Cyclic MgC3H (C2v) as a Candidate Molecule for Laser
Qiuyu Ye1, Mingda Li2, Xiaoguo Zhou3
1Department of Chemistry, University of Science and Technology of China, Hefei230026, China.
Abstract:
We report quantum chemistry calculations on the lowest electronic states (X̃2A1, Ã2B1, B̃2B2, and C̃2A1) of the lowest-energy conformer of MgC3H, namely, its planar cyclic form c-MgC3H (C2v), an elusive and intriguing molecule with both astrochemical and fundamental significance. Its equilibrium geometries and vibrational frequencies were calculated at the CASSCF(3,6)/cc-pVTZ level of theory, and the Franck-Condon factors (FCFs) between the ground and excited electronic states have been determined, based on which the excitation and emission spectra of vibronic transitions are predicted. Calculations suggest that c-MgC3H (C2v) is an excellent candidate for direct laser cooling of asymmetric-top molecules. Because the B̃2B2 - Ã2B1 transition is electric-dipole-forbidden, the B̃2B2 - X̃2A1 system can be used for photon cycling with exceptionally high efficiency. Pumping/repumping schemes for laser cooling have been proposed, and the predicted cooling efficiencies have been reported.
Related Concept Videos
UV–Vis Spectroscopy: Molecular Electronic Transitions
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to the...
Inductive Effects on Chemical Shift: Overview
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
IR Absorption Frequency: Hybridization
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...

