分子振转光谱的计算机辅助标识

介绍一种计算机辅助分子光谱振转标识的交互式软件,它的主要功能是根据二次逐差原理自动将谱线分组,挑取各个支带；然后用图解的方式,以谱线频率和强度为坐标轴,将选取的各组谱线按不同的颜色或线形绘成柱状图,清晰地显示出隐藏在复杂分子光谱中的振转结构；而且,同时可以作出Loomis-Wood图辅助光谱振转标识。将本软件应用到由三氯化磷和氦气放电生成的包含多种分子的复杂光谱中,取得了满意的结果,有效地辅助了光谱的振转分析。该软件适用于对称陀螺分子和轻微不对称陀螺分子和线形分子的光谱分析。     

High-Resolution Fourier Transform Emission Spectroscopy of the TiCl Radical in the 420-nm Region

Emission spectra of the TiCl radical in the 420-nm region have been observed at a resolution of 0.04 cm(-1) using a Fourier transform spectrometer. A new electronic assignment of (4)Gamma-X(4)Phi has been proposed. Rotational analysis has been provided for the 0-0 and 1-1 vibrational bands of the (4)Gamma(5/2)-X(4)Phi(3/2) and (4)Gamma(7/2)-X(4)Phi(5/2) spin components and the 0-0 band of (4)Gamma(9/2)-X(4)Phi(7/2). Copyright 2000 Academic Press.     

Rotationally Resolved REMPI Spectra of CaH in a Molecular Beam

Rotationally resolved spectra of the CaH radical using a supersonic molecular beam are reported. Thus, high energy resolution of the (1+1′) REMPI spectra corresponding to the A←X and B←X electronic transitions were measured which allowed for the first time a clear and precise analysis of the low rotational part (J≤7) of the CaH spectrum. A comparison with previous studies revealed that the commonly accepted energy separation between the two band heads of B−X (v′=1, v′=0) of 10 cm⁻¹ is not correct. A value of ca. 1.6 cm⁻¹ was found to be more realistic. On the other hand, the present study confirmed that the perturbation appears only for v′=1, N′>3 of the B state.     

Effect of Laser Injection Seeder on Rotationally Resolved Spectra of Benzonitrile

High resolution lasers are necessary to derive the most information from molecular spectra. However, their use uncovers some photophysical processes that compromise the ability to resolve rotational structure. We study the influence of laser optical mode structure on the high resolution spectra of the S1 states of benzonitrile in a supersonic molecular beam using an Ar^＋ pumped cw ring dye laser which is amplified by a pulsed Nd： YA G laser. The latter could be operated either in one optical mode by injecting （seeding） its oscillator with a single mode diode laser, or with many optical modes by not using the seeder. Rotationally resolved lines are obtained when the oscillator of the YAG laser are operated in one single optical mode, but only a continuum is seen when the YAG laser has multiple modes. It is argued that the ac Stark effect is the most probable reason for broadening and blurring the rotational lines.     

Absolute Quantifications of Oxy- and Deoxyhemoglobin Concentrations by Combination of Differentially Resolved Spectroscopy and Spatially Resolved Spectroscopy

This letter proposes a theoretical framework to calculate absolute concentrations of oxy- and deoxyhemoglobin using continuous-wave near-infrared spectroscopy. While previous methods on this topic require assumptions on constant blood volume, the proposed method does not. Equations for the absolute concentrations were derived from a combination of the modified Beer–Lambert equation and the theory of diffusion of photons in turbid media. The method has an advantage over and is theoretically consistent with previous methods. It needs yet to be evaluated in an experimental study.     

Terahertz Spectroscopy of the Amidogen Radical, NH2

The rotational spectrum of the NH2 radical in its &Xtilde;2B1 ground vibronic state was investigated between 614 and 1003 GHz. One hundred fifty-nine newly observed lines (188 hyperfine components) of six rotational transitions with 0 相似文献   

GaN激子跃迁的时间分辨光谱学研究

用时间分辨光谱学方法研究低压有机金属化学汽相沉积生长的ＧａＮ中自由，束缚激子（ＢＸ）的跃迁，讨论了这些跃迁的光致发光谱，复合寿命及其与温度的关系，给出了中性施主束缚激子和自由激子（ＦＸ）的辐射复合寿命分别为０．１２ｎｓ和０．４ｎｓ。     

Temporally Resolved Spectroscopy of Laser-Induced Carbon Ablation Plasmas

Temporally resolved emission spectra (360-630 nm) of carbon ablation plasmas produced during laser hole boring by a 25-ns duration 1-J ruby laser pulse are presented. The emitted line radiation originates from, C+++ to C+ depending upon the time relative to the laser pulse. Plasma temperatures of 12-14 eV during the laser pulse to about 4 eV, 140 ns after the laser pulse are obtained by comparing the spectroscopic results to a collisional-radiative equilibrium (CRE) model which bridges the gap between the local thermodynamic equilibrium (LTE) model and the coronal model.     

High-Resolution Visible Laser Spectroscopy of Cobalt Monochloride

The electronic spectrum of cobalt monochloride has been investigated from 415 to 725 nm using a laser-ablation/molecular-beam laser-induced fluorescence spectrometer. Two separate electronic systems with origins near 483.3 and 470.3 nm were observed. Data have been recorded for these two transitions at both low and high resolution. These transitions are now characterized as the [20.7]³Φ₄−X³Φ₄ and [21.3]³Φ₄−X³Φ₄ transitions. A low-resolution vibrational analysis and a high-resolution rotational analysis have been carried out for each system, resulting in accurate values for the ground and excited state vibrational spacings and effective rotational constants. In addition, the magnetic hyperfine structure resulting from the spin of the Co nucleus was resolved and the hyperfine constants were determined. Comparison of the CoCl spectrum with that of CoH and CoF has allowed the ground state electron configuration of (core)(10σ)²(4π)⁴(1δ)³(5π)³(11σ)² to be determined. The hyperfine constants support the electron promotion 11σ→12σ for the observed transitions.     

Application of High-Resolution NMR Spectroscopy in Analyzing Ionites

The ¹H and ¹³C NMR spectra of granulated carboxylic cationite MAC-3 and fibrous anionites FIBAN (A-5, A-7, and A-9) have been investigated. The dependence of the chemical shifts and times of spin–spin relaxation of the water protons and carbon nuclei of MAC-3 on the water content in a sample has been investigated. A comparison of the carbon spectra of polyelectolytes and FIBAN fibrous anionites swollen in water has been made. It is shown that the carbon spectra of the ionites swollen in water represent fairly narrow lines practically for all groups of the skeleton, and therefore the structure of the ionites can be analyzed using a high-resolution NMR.     

Laser-Induced Breakdown Spectroscopy Via the Spatially Resolved Technique Using Non-Gated Detector

We present a simple setup for laser-induced breakdown spectroscopy using the spatially resolved technique (SRLIBS). We show that, without any need for time-gated ICCD and pulse generator, the signal-to-background ratio is enhanced. We develop a homemade spectrograph with a movable slit located at its entrance to detect different parts of the plasma emission. For optimizing the position of the slit, we use the shadowgraphy technique to study the plasma expansion. In this low cost setup, with nanosecond laser pulses, we perform SRLIBS experiments on the plasma induced in air and iron. Our results show that the signal-to-background ratio for iron and air is enhanced up to 15 and 8 times, respectively.     

Electronic Spectroscopy of UO

Spectra for gas-phase uranium oxide have been analyzed to obtain molecular constants and provide a partial atlas of the visible and near infrared bands for the isotopomers²³⁸U¹⁶O,²³⁸U¹⁸O,²³⁵U¹⁶O, and²³⁵U¹⁸O. Nineteen bands of the²³⁸U¹⁶O,²³⁸U¹⁸O, and²³⁵U¹⁸O isotopomers were rotationally analyzed. With few exceptions, Ω assignments were unambiguously determined from observations of the first lines in at least two rotational branches. Accurate term values and rotational constants are reported.     

Coherent Derivation of Equations for Differential Spectroscopy and Spatially Resolved Spectroscopy: An Undergraduate Tutorial

Near-infrared spectroscopy (NIRS) is a spectroscopic method that is frequently used in health care and sports medicine to monitor oxygenation parameters in biological tissue. This tutorial provides a coherent derivation of equations for differential spectroscopy and spatially resolved spectroscopy, from basic theories to implementable equations. The basic theories are applicable to any kind of tissue oximeter but mainly focus on continuous-wave instruments.     

High-Resolution Solid-State NMR Spectroscopy of Steroids and Their Derivatives

Abstract: Steroids are an important class of organic compounds containing a vast array of biologically and physiologically essential molecules. Due to their availability, relatively straightforward derivatizability, and endogeneity, they are widely used in pharmacological applications. The investigation of molecular and physicochemical properties of active pharmaceutical ingredients (APIs) in the solid state is important, because these properties are directly related to their pharmacological activity. Several methods are available for this purpose. Solid-state NMR spectroscopy offers a nondestructive and flexible technique, providing both structural and dynamic information. It can be applied to every solid physical state (both crystalline and amorphous) as well as to materials with different compositions. The current article aims at gathering together some of the recent and most important studies in the area of high-resolution solid-state NMR spectroscopy of steroids and their derivatives completed with related theoretical reports not forgetting to outline the future remarks.     

Electronic Spectrum of the Antimony Monoxide Radical

The 0-1 band (4271.3 ?) of the B(2)Sigma(+)-X(2)(2)Pi(3/2) transition, the 0-6 band (4275 ?) of the H(2)Pi(3/2)-X(2)(2)Pi(3/2) transition, the 0-0 band (3776.2 ?) of the B(2)Sigma(+)-X(1)(2)Pi(1/2) transition, and the 2-0 (3251.3 ?) as well as the 3-0 (3194.2 ?) bands of the C(2)Sigma(-)-X(1)(2)Pi(1/2) transition of SbO have been photographed at high resolution using the single isotope of antimony (121)Sb. An unambiguous analysis of the rotational structure of all these bands has been carried out for the first time. The magnitude and sign of the Lambda doubling constant p(0) of the X(1)(2)Pi(1/2) state have been determined and as a result of that, the symmetry of the C state has been uniquely identified as C(2)Sigma(-). Accurate rotational constants of all the states involved have been determined by a global linear least-squares fit. Copyright 2000 Academic Press.     

Electronic Spectra of Radical Ions

Abstract

Organic molecules may accept an extra electron to form radical anions, R⁺, or give up an electron by ionization to form radical cations, R⁺. Some of the radical ions are relatively stable in their ground states in solution phase and can be readily characterized by spectroscopic methods. Electron spin resonance spectroscopy provides an ideal tool for the study of the unshared electron in these radical ions. Most radical ions are intensely colored and give characteristic absorption bands in the electronic spectra. Further, electronic spectroscopy is one of the few tools available for the study of the dianions, which are generally diamagnetic. Electronic spectroscopy is used not merely for the characterization of the ionic species in solution but also for the study of the chemical equilibria involving various kinds of ionic species.     

High-Resolution Fourier Transform Spectroscopy of Three Near-Infrared Transitions of NiF

The emission spectrum of the NiF radical has been recorded by high-resolution Fourier transform spectroscopy in the region 6000-12 000 cm⁻¹. Numerous new near-infrared bands were observed. In this paper three electronic transitions are analyzed leading to the identification of two new electronic states: a [12.0]²Φ_7/2 state and a [11.1]²Π_3/2 state located, respectively, at 12 008.89 and 11 096.05 cm⁻¹ above the X²Π_3/2 ground state. These electronic states can be correlated to the [3d⁸(³F)4s]²F atomic term of Ni⁺ as predicted by Carette et al. [J. Mol. Spectrosc.161, 323-335 (1993)].     

High-Resolution Survey of the Visible Spectrum of NiF by Fourier Transform Spectroscopy

High-resolution spectra of NiF have been recorded in emission by Fourier transform spectroscopy using a very stable discharge source. The 0-0 bands of 14 electronic transitions have been studied, 6 of them for the first time. This work confirms the presence of 5 low-lying spin components X²Π_3/2, [0.25]²Σ⁺, [0.83]A²Δ_5/2, [1.5]B²Σ⁺, and [2.2]A²Δ_3/2 as known from previous laser-induced fluorescence experiments. Eight electronic states are now identified in the 18 000-24 000 cm⁻¹ range above the ground X²Π_3/2 state. Electronic assignments for these excited states are not always obvious because of violations of the selection rules and unusual fine structure parameters. We think that some of the upper states are spin components of quartet states. In such a congested spectrum, high-resolution spectra are best analyzed in conjunction with an energy level diagram constructed mainly by dispersed low resolution laser-induced fluorescence.