マトリックスで分離されたフェニル基の赤外線スペクトル
A V Friderichsen1, J G Radziszewski, M R Nimlos
1Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.
Journal of the American Chemical Society
|July 18, 2001
まとめ
この研究は,アルゴン行列におけるフェニル基 (C(6) H(5) の正確な赤外線吸収スペクトルを示しています. これらの新しい測定は,フェニル基の振動周波数を改善し,以前のデータを置き換えました.
科学分野:
- 物理化学 物理化学
- スペクトロスコーピーは,スペクトロスコーピーを用います.
- 分子物理学 分子物理学
背景:
- フェニルラジカル (C(6) H(5) は,燃焼と大気化学における重要な中間物質である.
- フェニル基の正確な振動データは,その反応性とスペクトル特性を理解するために不可欠です.
- 以前のフェニルラジカル振動周波数の実験データには限界がありました.
研究 の 目的:
- アルゴン (Ar) マトリックスのフェニル基 (C(6) H(5) の赤外線吸収スペクトルを測定し,割り当てます.
- フェニル基の正確な振動周波数と偏振を決定する.
- フェニルラジカルに関する以前の実験値を更新し,置き換えることを目的としています.
主な方法:
- Arマトリックス内のフェニル基の赤外線吸収スペクトロスコピーは10Kで実施された.
- 3つの異なる方法を使用してフェニルラジカルの生成.
- 周波数シフトの比較のための5つのデュテラートイソトポメアの光譜分析.
- CO(2) またはNOの内部標準を使用して絶対赤外線強度の決定.
- 振動帯の偏振のための線形二極化の測定.
主要な成果:
- 実験的な振動周波数 (cm(-1)) と,フェニル基の a(1),b(1),b(2) モードに対する偏振を記録した.
- 実験的な周波数シフトと,デュテラートされた同位体に対する計算されたハーモニック周波数との比較.
- 絶対赤外線強度と振動帯の実験的偏振を決定した.
- ガス相振動周波数が推定され,マトリックス周波数は+/-1%以内であった.
結論:
- 測定された赤外線スペクトルは,フェニル基の包括的なデータセットを提供します.
- 実験の振動周波数は非常に正確で,以前に報告された値を上回ります.
- この研究は,フェニル基の理論的および実験的研究のための信頼できる基盤を確立します.
関連する概念動画
01:09Infrared (IR) Spectroscopy: Overview
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.
Different compounds display unique properties due to their...
Different compounds display unique properties due to their...
01:19IR Spectrum
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.
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete...
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete...
01:04¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
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,...
01:25IR 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...
01:03IR Frequency Region: Fingerprint Region
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.
The...
The...