Related Experiment Video
Updated: Jul 6, 2026
04:37
High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States
Published on: June 29, 2021
Shock-tube study of high-pressure H2O spectroscopy
V Nagali1, J T Herbon, D C Horning
1High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, California 94305-3032, USA. venu@oma-inc.com
Applied Optics
|March 8, 2008
Summary
This study accurately measured water-vapor absorption spectra under high-pressure and high-temperature conditions. The findings validate spectroscopic models for accurate atmospheric and combustion analysis.
Area of Science:
- Spectroscopy
- Physical Chemistry
- Atmospheric Science
Background:
- Accurate spectroscopic data for water vapor is crucial for atmospheric and combustion research.
- Existing models require validation under extreme conditions of high pressure and temperature.
Purpose of the Study:
- To probe water-vapor absorption features at high pressures (up to 65 atm) and temperatures (up to 1800 K).
- To validate and refine spectroscopic models using experimental measurements.
- To determine temperature-dependent broadening and shift parameters for water-vapor absorption lines.
Main Methods:
- Utilized a diode-laser source to probe water-vapor absorption in shock-heated H(2)O/N(2) and H(2)O/Ar mixtures.
- Employed Voigt line shapes and measured line parameters for absorbance calculations.
- Shifted calculated spectra to match experimental absorption scans to derive shift parameters.
Main Results:
- Calculated absorbances agreed within 10% with measured values at specific wavelengths (7185.4 and 7117.4 cm(-1)).
- Spectroscopic models (HITRAN, HITEMP) showed good agreement (within 25%) with measurements across 600-1800 K.
- Combined line parameters yielded absorption coefficients within 15% of experimental data.
Conclusions:
- Experimental validation confirms the accuracy of spectroscopic models for water vapor under high-pressure and high-temperature conditions.
- The derived temperature-dependent shift parameters enhance the predictive capability of spectroscopic databases.
- This research provides reliable spectroscopic data for advanced applications in combustion and atmospheric modeling.
Related Concept Videos
02:39Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
01:16Shock Waves
While deriving the Doppler formula for the observed frequency of a sound wave, it is assumed that the speed of sound in the medium is greater than the source's speed through it. When this condition is breached, a shock wave occurs.
When the source's speed approaches the speed of sound, constructive interference between successive wavefronts emitted by the source occurs immediately behind it. Initially, scientists believed that this constructive interference would result in such high pressures...
When the source's speed approaches the speed of sound, constructive interference between successive wavefronts emitted by the source occurs immediately behind it. Initially, scientists believed that this constructive interference would result in such high pressures...
03:02Constant Pressure Calorimetry
Calorimetry is a technique used to measure the amount of heat involved in a chemical or physical process or to measure the heat transferred to or from a substance. The heat is exchanged with a calibrated and insulated device called the calorimeter. Calorimetry experiments are based on the assumption that there is no heat exchange between the insulated calorimeter and the external environment. The well-insulated calorimeters prevent the transfer of heat between the calorimeter and its external...
01:21Atomic Absorption Spectroscopy: Lab
For AAS measurements, samples must be introduced as clear solutions, often requiring extensive preliminary treatment to dissolve materials like soils, animal tissues, and minerals. Common methods for sample preparation include treatment with hot mineral acids, wet ashing, combustion in closed containers, high-temperature ashing, or fusion with reagents.
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing nebulizer...
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing nebulizer...
00:48¹H NMR of Labile Protons: Deuterium (²H) Substitution
This lesson illustrates the role of deuterium substitution in simplifying the NMR spectrum of compounds comprising labile protons. One method employed is the use of deuterium. Amongst the three isotopes of hydrogen, deuterium (2H) has a nucleus composed of one proton and one neutron. When the D2O solvent is added to a pure dry ethanol solution, its labile proton is substituted with deuterium.
01:25Atomic Absorption Spectroscopy: Atomization Methods
Atomic Absorption Spectroscopy (AAS) atomizes samples through flame atomization or electrothermal atomization. Flame atomization typically involves a nebulizer and spray chamber assembly to combine the sample with a fuel–oxidant mixture, creating a fine aerosol mist that enters a burner. Typically, the fuel and oxidant are combined in an approximately stoichiometric ratio. However, for atoms that are easily oxidized, a fuel-rich mixture may be more advantageous. Only about 5% of the aerosol...