Related Experiment Video
Updated: Jul 31, 2026
09:40
Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown
Published on: February 14, 2014
Absolute nu(2) Line Intensities of HOCl by Simultaneous Measurements in the Infrared with a Tunable Diode Laser and
Vander Auwera J1, Kleffmann, Flaud
1Laboratoire de Chimie Physique Moléculaire C.P. 160/09, Université Libre de Bruxelles, 50 avenue F. D. Roosevelt, Brussels, B-1050, Belgium
Journal of Molecular Spectroscopy
|October 18, 2000
Summary
This study measured absolute line intensities for hypochlorous acid (HOCl) isotopomers. New measurements of the nu(2) band transition dipole moment are significantly lower than previous values.
Area of Science:
- Molecular Spectroscopy
- Atmospheric Chemistry
Background:
- Hypochlorous acid (HOCl) is a reactive species important in atmospheric chemistry.
- Accurate spectroscopic data for HOCl is crucial for understanding its behavior and concentration.
- Previous measurements of HOCl line intensities may have inaccuracies.
Purpose of the Study:
- To accurately measure absolute line intensities in the nu(2) fundamental band of HOCl isotopomers.
- To determine the square of the nu(2) band vibrational transition dipole moment for HO(35)Cl and HO(37)Cl.
- To refine spectroscopic models for HOCl.
Main Methods:
- Simultaneous recording of far-infrared (FIR) pure rotation and infrared (IR) nu(2) band spectra of HOCl.
- Utilizing Stark effect measurements to determine HOCl partial pressure from FIR spectra.
- Calibrating IR line intensities using simultaneously measured FIR data and known FIR line intensities.
Main Results:
- Absolute line intensities in the nu(2) fundamental band of HOCl were measured.
- The square of the nu(2) band vibrational transition dipole moment was determined to be 0.013947(23) D(2) for HO(35)Cl and 0.013870(51) D(2) for HO(37)Cl.
- These values are 29-73% lower than previously reported measurements.
Conclusions:
- The determined transition dipole moments provide more accurate spectroscopic data for HOCl.
- The findings necessitate a revision of previous spectroscopic parameters for HOCl.
- The study contributes to a better understanding of HOCl in atmospheric and chemical processes.
Related Concept Videos
01:192D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
01:24IR Spectroscopy: Molecular Vibration Overview
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
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...
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...
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to the...
According to Hooke's law, the vibrational frequency is directly proportional to the...
01:21IR Absorption Frequency: Hybridization
Hydrocarbons such as alkanes, alkenes, and alkynes show characteristic C–H stretching absorption bands. These IR stretching frequencies depend on the hybridization of the involved carbon atom and can be explained in terms of the s character of each hybridized atomic orbital.
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...
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...
01:22Atomic Absorption Spectroscopy: Instrumentation
An atomic absorption spectrophotometer (AAS) comprises several components: a radiation source, an atomizer, a monochromator, and a detector. The radiation source can be a hollow-cathode lamp (HCL) or an electrodeless-discharge lamp (EDL), both of which provide a narrow emission line of the required wavelength. However, some instruments use continuum sources and high-resolution monochromators to achieve a narrow range of radiation.
The atomizer used in AAS can be either a flame atomizer or an...
The atomizer used in AAS can be either a flame atomizer or an...