Related Experiment Video
Updated: Jul 4, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
State-selective predissociation dynamics of methylamines: the vibronic and HD effects on the conical intersection
Doo-Sik Ahn1, Jeongmook Lee, Jeong-Mo Choi
1Department of Chemistry and School of Molecular Science (BK21), KAIST, Daejeon 305-701, Republic of Korea.
Abstract:
The photodissociation dynamics of methylamines (CH(3)NH(2) and CD(3)ND(2)) on the first electronically excited state has been investigated using the velocity map ion imaging technique probing the H or D fragment. Two distinct velocity components are found in the H(D) translational energy distribution, implying the existence of two different reaction pathways for the bond dissociation. The high H(D) velocity component with the small internal energy of the radical fragment is ascribed to the N-H(D) fragmentation via the coupling of S(1) to the upper-lying S(2) repulsive potential energy surface along the N-H(D) bond elongation axis. Dissociation on the ground S(0) state prepared via the nonadiabatic dynamics at the conical intersection should be responsible for the slow H(D) fragment. Several S(1) vibronic states of methylamines including the zero-point level and nnu(9) states (n=1, 2, or 3) are exclusively chosen in order to explore the effect of the initial quantum content on the chemical reaction dynamics. The branching ratio of the fast and slow components is found to be sensitive to the initial vibronic state for the N-H bond dissociation of CH(3)NH(2), whereas it is little affected in the N-D dissociation event of CD(3)ND(2). The fast component is found to be more dominant in the translational distribution of D from CD(3)ND(2) than it is in that of H from CH(3)NH(2). The experimental result is discussed with a plausible mechanism of the conical intersection dynamics.
More Related Videos
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
08:54Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
Published on: January 25, 2020
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Inductive Effects on Chemical Shift: Overview
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
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...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR