Descriptive,interactive computer-assisted interpretation of infrared spectra

A knowledge-based system for interpreting infrared spectra which explains the rationale behind the interpretation process, in a step-by-step fashion, has been developed. The user, having been informed of the basis for decisions made during interpretation of the data, is better able to understand, and thereby to utilize, the results. Additional features allow the informed user to participate in the interpretation of the spectral data, thereby increasing the quality and quantity of data available to the system. In addition to assisting researchers, this system can be used for computer- assisted instruction of the infrared spectral interpretation process.     

Computer-aided Interpretation of Proton Nuclear Magnetic Resonance Spectra (Ⅰ)——An Artificial Intelligence System for Interpretation of Proton NMR Spectra of Polymers

An artificial intelligence system for interpretation of proton NMR spectra of polymers is reported in this paper. The system, including spectra data base, knowledge data base and reasoning engine, is based on the characteristics of the proton NMR spectra of polymers and the spectra interpretation experiences of specialist. The system can partly simulate human thinking and interpret proton NMR spectra of polymers at different levels of sophistication. The program in the system was written in Turbo Prolog 2.0 and translated into machine language by computer compiler. It has been tested on an IBM PC/XT computer and a satisfactory result was given.     

Dynamic,computer-assisted interpretation of infrared spectra of condensed-phase mixtures

A knowledge-based system, MIXIR, designed to assist researchers in interpreting the infrared spectra of condensed-phase mixtures is described. This system overcomes many of the inherent limitations of static-rule-based systems. An iterative problem-solving approach is permitted, making use of information gained during the interpretation process. The dynamic rule selection and significance evaluation alos allow the user to provide information on the sample matrix, or to select a subset of the compounds for rule derivation. The MIXIR system was evaluated with a knowledge base compiled using IRBASE, a complementary program, and a test set of 20 mixtures.     

Automatic spectra interpretation,structure generation,and ranking

A new rule-based spectra interpretation system is described. It directly processes spectral files generated by spectrometers. Its internal information representation and the simultaneous use of several spectroscopic methods allow for the achievement of both high reliability and good performance. For small and medium sized molecules, the new program is capable of automatically reducing the solution space to under 3%.     

Molecular conformations of a partially halogenated ether: A study based on infrared spectroscopy and density functional theory calculations

A new partially halogenated ether (ClCF₂CF(CF₃)OCF₂CH₃) has been synthesized and characterized using DSC, GC, ¹H and ¹⁹F NMR, IR. The experimental infrared spectra of this “flexible” molecule have been successfully interpreted on the basis of reliable Density Functional Theory calculations. An efficient method useful for the identification of the many stable conformers has been developed and applied. Infrared spectra of the stable conformers have been simulated after full geometry optimization. The results obtained allow detection of conformation-sensitive bands, making possible the interpretation of fine details in the spectra.     

红外光谱结构解析专家系统

本文报道一个可辅助化学家进行红外光谱结构解析的新的专家系统。它由5个基本部分组成:知识库、推理机、数据库、知识获取模块和解释模块。系统用TurboPROLOG人工智能语言实现。与其它光谱解析系统相比较,本系统具有下述特点:方便友好的用户界面,两种知识库管理手段,数种解释功能。可在IBMPC/XT及其兼容机上运行。系统的另一个重要特点是能模拟有经验的化学家解析光谱、推断完整分子结构的推理方法。     

A New Expert System for Structural Interpretation of IR Spectra

A new expert system has been developed which can be used to aid chemists in structural interpretation of infrared spectra. The system consists of five essential portions: knowledge-base , inference engine, database, knowledge-acquisition module and explanatory interface. The system is implemented in Turbo PROLOG artificial intelligence language. Compared with other spectral interpretation systems this system is of the following advantages, i. e. the system has a friendly user interface, two kinds of methods for managing toowledge-base, several useful explanatory facilities such as why and how should explanation be made, etc. ; in addition, it can be run on the IBM PC/XT and its compatible microcomputers. Another important feature of the system is that it can simulate the reasoning procedure by which experienced chemists may interpret spectra as well as deduce complete molecular structures. So the system can also be used as a helpful learning tool for training chemistry students in IR spectrum interpreta     

IR-spectra and phases structure of sialons

IR-spectra of Si–Al–O–N system ceramic materials with prevailing phase maintenance—X-phase, β-sialon, 15R obtained by carbothermal reduction and simultaneous nitration of kaolin at various proportions of kaolin and carbon were studied. Complex contours of absorption bands are divided into separate components. Separate components contours are approximated with Gauss function. Integral intensities of absorption bands are calculated. The totality of IR-spectra data of silicon and aluminium nitride absorption spectra, corundum as well as kaolin absorption spectra was used for interpretation of sialon spectra. It was shown that IR spectroscopy data correlate well with chemical structure of examined sialons and allow to obtain information enlarging X-ray data.     

Identification de composes inconnus en spectrometrie de masse par Comparaison a une Bibliotheque sur Cartouches Digitales

An automatic method for interpretation of mass spectra is described. This approach uses the comparison of unknown spectra with those included in a library of standard references. The spectra are stored on digital magnetic tape. Several hundred spectra can be recorded on a cartridge. The tape unit is connected to a minicomputer. This system offers many advantages and is very well suited for medium sized laboratories. The series of compounds studied are the olefins, compounds with very similar spectra, so the method of interpretation has to be powerful. The different parts of the identification algorithm are discussed. The results and experimentation are also presented.     

Ion pairs formed by alkali metals. Complex of caesium with 4-nitropyridine

The ESR spectra of the 4-nitropyridine/caesium system in dimethoxyethane have been measured in the range of temperature between ?100 and +20°C. These spectra are drastically different from those of the ion pairs obtained with the lighter alkali metals, and an interpretation is offered.     

1H and 13C NMR study of dihydro derivatives of methylphenobarbital

Sodium borohydride reduction of methylphenobarbital leads to the formation of two different dihydroderivatives, reduced either in position 4 or position 6. The structures of the derivatives have been determined through analysis of the ¹H and ¹³C NMR spectra of phenobarbital, methylphenobarbital and their derivatives. Detailed interpretation of the spectra and the resulting spectral parameters indicate conformations where the hydroxyl groups are axial and trans to the ethyl group. In these configurations the phenyl ring becomes equatorial. The results also allow an unambiguous assignment of the resonances of the phenyl carbons 2′(6′) and 3′(5′) of phenobarbital and the carbonyl carbons 4 and 6 of methylphenobarbital, differing interpretations having been previously advanced in the literature.     

A comparison of the static SIMS and G‐SIMS spectra of biodegradable homo‐polyesters

Static SIMS (SSIMS) is a surface analytical technique capable of providing molecular chemical information from solids. A major barrier to the wider take‐up of the technique is the complexity associated with the interpretation of SSIMS spectra. Quality of the interpretation depends on the expertise of analysts and making references to the limited mass spectral libraries. For many materials, there are no SSIMS library spectra. A new library‐independent method, G‐SIMS, is capable of facilitating the interpretation of SSIMS data. G‐SIMS spectra contain parent fragments, which are formed without substantial degradation or rearrangements, and highlight molecular fragments, which are directly related to the surface. In our study, G‐SIMS has been tested on medically relevant biodegradable polyester series, including poly (glycolic acid) (PGA), poly‐l‐(lactic acid) (PLA), poly‐β‐(hydroxybutyrate) (PHB) and poly‐ε‐(caprolactone) (PCL). The polyester series chosen here have closely related structures, which allow us to explore the capabilities of G‐SIMS. The G‐SIMS spectra have facilitated the identification of different polyesters by exhibiting mainly characteristic ions, representative of the polymers' molecular structures. The results also indicated that for the chosen polyester series, the larger the repeating monomer structures, the smaller the maximum number of repeat units were seen in the G‐SIMS spectra. The G‐SIMS spectra for the homologous polyester series have provided an insight into the fragmentation mechanisms as a function of repeating monomer molecular weights and structures. Copyright © 2008 John Wiley & Sons, Ltd.     

Validation of a computer-program for the interpretation of infrared spectra

The capability of a modern interpretation system for IR spectra has been tested, in which the process of structural assignment is modelled by methods of fuzzy logic. Figures of merit were generated for different interpretation algorithms. These figures of merit permit the validation as well as a comparison of independent interpretation systems. The influence of the sample preparation practice onto the information content of the resulting spectrum has been evaluated as well. Automatically generated band tables show only restricted reliability. Received: 13 February 1997 / Revised: 1 April 1997 / Accepted: 3 April 1997     

Validation of a computer-program for the interpretation of infrared spectra

The capability of a modern interpretation system for IR spectra has been tested, in which the process of structural assignment is modelled by methods of fuzzy logic. Figures of merit were generated for different interpretation algorithms. These figures of merit permit the validation as well as a comparison of independent interpretation systems. The influence of the sample preparation practice onto the information content of the resulting spectrum has been evaluated as well. Automatically generated band tables show only restricted reliability. Received: 13 February 1997 / Revised: 1 April 1997 / Accepted: 3 April 1997     

Interpretation of analytical patterns from the output of chaotic dynamical memories

A fundamental study has been carried out to use a nonlinear dynamic system, Freeman's KIII model, for pattern recognition in analytical chemistry. Filtering of the output of the neuron activity traces in the gamma range has been studied by applying a fast Fourier transform filter. Different possibilities for interpretation of the system output have been investigated. Preliminary results are demonstrated for classification of drugs based on their spectra in the mid infrared range.     

The primary electroviscous effect of polystyrene latexes

An investigation on the primary electroviscous effect of polystyrene latexes has been made. Capillary viscometers of Ubbelohde type have been used. The comparison of the results obtained with the theories allow us to conclude that the effect is underestimated for low electrolyte concentrations. We suggest that this underestimation is due to an additional surface conductance into the electric double layer. This interpretation is consistent with previous studies on electrophoretic mobility of the same system.     

The Bouguer-Beer-Lambert Law: Shining Light on the Obscure

The Beer-Lambert law is unquestionably the most important law in optical spectroscopy and indispensable for the qualitative and quantitative interpretation of spectroscopic data. As such, every spectroscopist should know its limits and potential pitfalls, arising from its application, by heart. It is the goal of this work to review these limits and pitfalls, as well as to provide solutions and explanations to guide the reader. This guidance will allow a deeper understanding of spectral features, which cannot be explained by the Beer-Lambert law, because they arise from electromagnetic effects/the wave nature of light. Those features include band shifts and intensity changes based exclusively upon optical conditions, i. e. the method chosen to record the spectra, the substrate and the form of the sample. As such, the review will be an essential tool towards a full understanding of optical spectra and their quantitative interpretation based not only on oscillator positions, but also on their strengths and damping constants.     

Systematic computer-aided interpretation of vibrational spectra

The interpretation process for vibrational spectra is considered in detail. The concepts of spectral data, structural elements and basic file are described. Two parameters proved to be useful for expressing the degree of correlation of wavenumber regions and structural elements. Three types of intervals are distinguished. A computer program has been developed to obtain these intervals. Factors influencing the results of an interpretation system are discussed and possible criteria are reported.     

Interpretation of analytical patterns from the output of chaotic dynamical memories

A fundamental study has been carried out to use a nonlinear dynamic system, Freeman’s KIII model, for pattern recognition in analytical chemistry. Filtering of the output of the neuron activity traces in the gamma range has been studied by applying a fast Fourier transform filter. Different possibilities for interpretation of the system output have been investigated. Preliminary results are demonstrated for classification of drugs based on their spectra in the mid infrared range.     

Systematic computer-aided interpretation of vibrational spectra

The diagnostic value of an interpretation system for vibrational spectra has been investigated in relation to the number of structural units the system can cope with. For five structural units the correlated wavenumber intervals are derived from three infrared and three Raman files by the CRISE program. The interpretative value of each interval in relation to the intensity threshold is discussed. For most intervals a decrease is found on increasing the number of structural units.