Related Experiment Video
Updated: Oct 2, 2025
12:21
Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators
Published on: April 4, 2016
11.4K
Mapping partial wave dynamics in scattering resonances by rotational de-excitation collisions
Tim de Jongh1,2, Quan Shuai1,3, Grite L Abma1
1Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands.
Nature Chemistry
|February 25, 2022
Summary
This study reveals how individual partial waves evolve during low-energy NO-He collisions by tuning energies to scattering resonances. This allows detailed observation of angular momentum transfer and collision dynamics.
Area of Science:
- Chemical Physics
- Quantum Mechanics
- Atomic and Molecular Collisions
Background:
- Collision outcomes typically average over many partial waves, obscuring individual dynamics.
- The impact parameter, or miss distance, is crucial in describing quantum mechanical collisions via partial waves.
Purpose of the Study:
- To probe the evolution of individual partial waves during low-energy nitric oxide-helium (NO-He) collisions.
- To investigate the dynamics of angular momentum transfer in molecular collisions.
Main Methods:
- Tuning collision energies to specific scattering resonances (0.4–6 cm⁻¹).
- Preparing NO in rotationally excited states.
- Studying rotational de-excitation collisions and analyzing differential cross-sections.
Main Results:
- Identified conditions with a limited set of initial partial waves.
- Observed the evolution of a single quantum of angular momentum during collisions.
- Obtained detailed insights into partial wave dynamics through distinct cross-section "fingerprints".
Conclusions:
- Low-energy NO-He collisions at specific resonances allow for the study of individual partial wave evolution.
- Rotational de-excitation collisions serve as a sensitive probe of time-reversed excitation processes.
- This method offers superior energy and angular resolution for collision dynamics.
Related Concept Videos
01:12Double Resonance Techniques: Overview
331
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
331
01:23Atomic Nuclei: Nuclear Relaxation Processes
751
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
751
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
942
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
942
01:20Raman Spectroscopy: Overview
724
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
724
01:05Atomic Nuclei: Magnetic Resonance
788
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
788
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.1K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.1K