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IR Spectrum

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When infrared (IR) radiation passes through a molecule, the bonds stretch or bend by absorbing the radiation. This absorption creates the molecule's absorption spectrum, which is the plot of its percentage transmittance versus wavenumber.
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IR Frequency Region: Fingerprint Region

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IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the C=O, C=N, and C=C occur between 1600–1850 cm−1.
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IR Spectrometers

There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR spectrometer, a beam of infrared radiation produced by a hot wire is divided into two parallel equal-intensity beams using mirrors. One beam passes through the sample, while another is a reference beam. The beams then move through the monochromator, which separates the radiations into a continuous spectrum of different frequencies. The...

Infrared (IR) Spectroscopy: Overview

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When electromagnetic radiation passes through a material, atoms or molecules transition from a lower to a higher energy state by absorbing radiation corresponding to the energy difference between the two states. The absorption of infrared (IR) radiation causes transitions between vibrational energy levels in a molecule. Therefore, IR spectroscopy is a useful analytical tool for determining the molecular structure of molecules.
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Attenuated total reflectance (ATR) infrared spectroscopy is a powerful analytical technique used to study the composition of materials. It is widely employed in chemistry, materials science, forensic science, and other fields where sample characterization is required. ATR has several advantages over traditional transmission IR spectroscopy, including the requirement of little to no sample preparation and the ability to analyze a wide range of samples.
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IR Spectroscopy: Molecular Vibration Overview

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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.
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Infrared passbands for clear-air-turbulence detection.

P M Kuhn, I G Nolt, L P Stearns

|August 18, 2009

Summary

This summary is machine-generated.

Infrared radiometers can detect clear air turbulence (CAT) in real time. An optimal infrared filter passband and higher aircraft altitude enhance CAT detection reliability and alert time.

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Area of Science:

Atmospheric science
Aerospace engineering
Remote sensing

Background:

Clear air turbulence (CAT) poses a significant risk to aviation safety.
Real-time detection of CAT is crucial for mitigating flight hazards.
Existing detection methods have limitations in reliability and alert time.

Purpose of the Study:

To investigate the effectiveness of infrared radiometry for real-time CAT detection.
To determine the optimal infrared filter passband for maximizing alert time and reliability.
To analyze the impact of aircraft altitude on CAT detection performance.

Main Methods:

Utilized an infrared radiometer for real-time CAT detection.
Analyzed data based on varying infrared filter passbands (26-35 micrometers).
Evaluated the influence of different aircraft altitudes on detection parameters.

Main Results:

A passband of 26 to 35 micrometers was found to be optimal for CAT detection.
The system provided alert times ranging from 1.5 to 6.0 minutes.
Increased aircraft altitude correlated with longer alert times due to reduced atmospheric absorption.

Conclusions:

Infrared radiometry offers a viable solution for real-time CAT detection.
Optimizing the infrared filter passband and utilizing higher altitudes enhance aviation safety by providing earlier warnings.
Further research can refine the system for improved performance in diverse atmospheric conditions.