The NIST Chemistry WebBook provides users with easy access to chemical and physical property data for chemical species through the internet. The data provided in the site are from collections maintained by the NIST Standard Reference Data Program and outside contributors. Data in the WebBook system are organized by chemical species. The WebBook system allows users to search for chemical species by various means. Once the desired species has been identified, the system will display data for the species. Data include thermochemical properties of species and reactions, thermophysical properties of species, and optical, electronic and mass spectra.

The NIST DART-MS Forensics Database is an evaluated collection of in-source collisionally-induced dissociation (is-CID) mass spectra of compounds of interest to the forensics community (e.g. seized drugs, cutting agents, etc.). The is-CID mass spectra were collected using Direct Analysis in Real-Time (DART) Mass Spectrometry (MS), either by NIST scientists or by contributing agencies noted per compound. The database is provided as a general-purpose structure data file (.SDF). For users on Windows operating systems, the .SDF format library can be converted to NIST MS Search format using Lib2NIST and then explored using NIST MS Search v2.4 for general mass spectral analysis. These software tools can be downloaded at https://chemdata.nist.gov. The database is now (09-28-2021) also provided in R data format (.RDS) for use with the R programming language. This database, also commonly referred to as a library, is one in a series of high-quality mass spectral libraries/databases produced by NIST (see NIST SRD 1a, https://dx.doi.org/10.18434/T4H594).

The NDRL/NIST Solution Kinetics Database contains data on rate constants for solution-phase chemical reactions. The database is designed to be searched by reactants, products, solvents, or any combination of these. In addition, the bibliography may be searched by author name, title words, journal, page(s), and/or year. This is not the same database as the one at Notre Dame, although both databases share a common data source.

Materials discovery and development necessarily begins with the preparation and identification of product phase(s). Crystalline compounds can be identified by their characteristic diffraction patterns using X-rays, neutrons, and or electrons. An estimated 20,000 X-ray diffractometers and a comparable number of electron microscopes are used daily in materials research and development laboratories for this purpose. Access to crystal structure data is a critical step in solving research and applications problems in materials researches, and these data are of interest to analysts in areas such as materials design, property prediction and compound identification. NIST Crystallographic Data Center, in collaboration with partners all over the world, evaluates and disseminates chemical, physical and crystallographic information published on these materials. NIST Standard Reference Database 3: NIST Inorganic Crystal Structure Database (NIST ICSD) is a comprehensive collection of crystal structure data of nonorganic compounds (including inorganics, ceramics, minerals, pure elements, metals, and intermetallic systems) containing over 210,000 entries and covering the literature from 1913. NIST ICSD includes entries that fall into the following categories: full structure data from experimental refinement or derived from their iso-structural structure types, theoretically predicted structures from computer simulations, as well as partially characterized structures. The NIST ICSD web application provides materials researchers with a user-friendly interface to search the database based on bibliographic information, chemistry, unit cell, space group, experimental settings, mineral name/group and other derived data from expert evaluation. In addition, it also provides users with functions to easily create and examine results from various crystallographic computations, such as reduced cell, bond distance/angle, calculated powder diffraction data, and structure standardization.

The NIST Chemical Kinetics Database includes essentially all reported kinetics results for thermal gas-phase chemical reactions. The database is designed to be searched for kinetics data based on the specific reactants involved, for reactions resulting in specified products, for all the reactions of a particular species, or for various combinations of these. In addition, the bibliography can be searched by author name or combination of names. The database contains in excess of 38,000 separate reaction records for over 11,700 distinct reactant pairs. These data have been abstracted from over 12,000 papers with literature coverage through early 2000. Rate constant records for a specified reaction are found by searching the Reaction Database. All rate constant records for that reaction are returned, with a link to 'Details' on that record. Each rate constant record contains the following information (as available): a) Reactants and, if defined, reaction products; b) Rate parameters: A, n, Ea/R, where k = A (T/298)*n exp[-(Ea/R)/T], where T is the temperature in Kelvins; c) Uncertainty in A, n, and Ea/R, if reported; d) Temperature range of experiment or temperature range of validity of a review or theoretical paper; e) Pressure range and bulk gas of the experiment; f) Data type of the record (i.e., experimental, relative rate measurement, theoretical calculation, modeling result, etc.). If the result is a relative rate measurement, then the reaction to which the rate is relative is also given; g) Experimental procedure, including separate fields for the description of the apparatus, the time resolution of the experiment, and the excitation technique. A majority of contemporary chemical kinetics methods are represented. The Kinetics Database is being expanded to include other resources for the convenience of the users. Presently this includes direct links to the corresponding NIST WebBook page for all substances for which such a link is possible. This is indicated by underling and highlighting the species. The WebBook provides thermodynamic, spectral, and other data on the species. Note that the link to the WebBook is opened as a new frame in your browser.

This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 4th Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.

The Inorganic Crystal Structure Database (ICSD) is produced cooperatively by the Fachinformationszentrum Karlsruhe (FIZ) and the National Institute of Standards and Technology (NIST). Components and devices used in a broad spectrum of technology sectors such as health care, communications, energy and electronics are manufactured from crystalline materials; the development of advanced crystalline materials requires accurate crystal-structure data. SRD 84 ICSD provides critically evaluated, comprehensive crystal-structure data and search software that enable phase identification by their characteristic diffraction patterns using X-rays, neutrons and electrons. SRD 84 ICSD contains full crystallographic and atomic-position information for more than 180,000 non-organic materials, including inorganics, ceramics, minerals, pure elements, metals and intermetallics, published in literature from 1913 through the present. ICSD is updated twice a year, with each update comprising about 2,000 to 10,000 new or re-evaluated entries. Data items include bibliographic information, compound designation such as chemical name, chemical formula, mineral name; and crystallographic parameters such as unit cell, space group, element symbol with numbering, oxidation state, multiplicity for Wyckoff position, x,y,z coordinates, site occupation, thermal parameters and reliability index R, among others. A free demonstration CD which includes a comprehensive user interface, FindIt, for a demo database is available upon request or can be downloaded from the website https://www.nist.gov/srd/nist-standard-reference-database-84.

The NIST Computational Chemistry Comparison and Benchmark Database is a collection of experimental and ab initio thermochemical properties for a selected set of gas-phase molecules. The goals are to provide a benchmark set of experimental data for the evaluation of ab initio computational methods and allow the comparison between different ab initio computational methods for the prediction of gas-phase thermochemical properties. The data files linked to this record are a subset of the experimental data present in the CCCBDB.

This data collection contains 5,228 infrared spectra of different compounds along with chemical structures for most of them. Spectra are provided on a CD-ROM in the JCAMP-DX (Joint Committee for Atomic and Molecular Physical Data 'Data Exchange') format. Chemical structures are provided in the MOL-file format. The IR data originated from two sources, from the so-called 'EPA Vapor-Phase IR Library' and from NIST laboratories. The data have been sub-divided in two ways: 1) as concatenated JCAMP and SDF files (concatenated MOL-files) and 2) in individual files where each spectrum and structure is provided in a separate JCAMP and MOL file, using file names containing the CAS registry number of the compound. Important Note: All spectra were measured in the gas phase by GC/IR (gas chromatography/infrared spectroscopy), hence concentrations in the IR cell are not known or estimable. Molar absorption coefficients are not reported. This data provides only relative absorption coefficients as a function of wavelength which can be used for identification, not quantification.

NIST X-ray Photoelectron Spectroscopy Database XPS contains over 33,000 data records that can be used for the identification of unknown lines, retrieval of data for selected elements (binding energy, Auger kinetic energy, chemical shift, and surface or interface core-level shift), retrieval of data for selected compounds (according to chemical name, selected groups of elements, or chemical classes), display of Wagner plots, and retrieval of data by scientific citation. For the newer data records, additional information is provided on the specimen material, the conditions of measurement, and the analysis of the data. Version 5.0 includes the addition of Digital Object Identifiers (DOI) to each of the citations. Additionally, Version 5.0 has new features including chemical shift plots, custom-built components for displaying both formatted molecular formulas and formatted spectral lines, and spectral sorting functions of photoelectron lines and Auger Parameters.

This version of NIST Standard Reference Database 46 is a major enhancement to this widely used database which provides comprehensive coverage of interactions for aqueous systems of organic and inorganic ligands with protons and various metal ions and is based on the six-volume Critical Stability Constants by Martell and Smith. The new version contains 225 additional ligands, new data, data printing, rapid bibliography searching and more streamlined commands. New literature has resulted in revision and upgrading of 30% of previous data. Entire contents are critically selected for accuracy and consistency.

This page, "Carbon dioxide", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

Special Database 19 contains NIST's entire corpus of training materials for handprinted document and character recognition. It publishes Handprinted Sample Forms from 3600 writers, 810,000 character images isolated from their forms, ground truth classifications for those images, reference forms for further data collection, and software utilities for image management and handling. there are two editions of the databases. One is the original database with the images in mis or pct format. It also includes software to open and manipulate the data. The second edition has the images all in PNG format.

The NIST Electron Inelastic-Mean-Free-Path Database provides values of electron inelastic mean free paths (IMFPs) principally for use in surface analysis by Auger-electron spectroscopy and X-ray photoelectron spectroscopy. The database includes IMFPs calculated from experimental optical data and IMFPs measured by elastic-peak electron spectroscopy. If no calculated or measured IMFPs are available for a material of interest, values can be estimated from the predictive IMFP formulae of Tanuma et al. and of Gries. IMFPs are available for electron energies between 50 eV and 10,000 eV although most of the available data are for energies less than 2,000 eV. A critical review of calculated and measured IMFPs has been published [C. J. Powell and A. Jablonski, J. Phys. Chem. Ref. Data 28, 19 (1999)].

The 1999 Semiconductor Industry Association (SIA) International Technology Roadmap for Semiconductors (ITRS) identifies 'Equipment Modeling' as first in a list of 'Technology Requirements' and states that 'the drivers for equipment modeling are equipment design, process control, . . . ' The ITRS indicates that continuing research is needed to obtain experimental data for 'transport and thermal constants.' This Project will generate transport and thermodynamic property data for the gases used in semiconductor processing. The data will be useful for equipment modeling in chemical vapor deposition (CVD) processes and the data will also provide a rational basis for the calibration of mass flow controllers (MFCs) used to meter process gases. NIST is measuring the thermophysical properties of the process gases, the 'surrogate' gases, and binary mixtures of process and carrier gases. The process gases are used in CVD and the surrogate gases are used to calibrate MFCs. The results will be disseminated in this data base providing the heat capacity, thermal conductivity, viscosity, and the virial coefficients for the virial equation of state providing the pressure-density-temperature relation for the process gases.

This page, "Aspirin", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

The IUPAC Solubility Data Series Volumes 1-103 (1979 to 2014) are made available online. Volumes 1-19 and 39-65 are available as scanned and OCR'd single PDF files. Volumes 20-38 are available with each volume indexed and sectioned into multiple PDF files that can browsed using an online table of contents. Volumes 66-103 are available through links to the document at the Journal of Physical and Chemical Reference Data. The electronic part of the database contains 67,500 solubility measurements, compiled from 18 volumes of the IUPAC Solubility Data Series. There are about 1800 chemical substances in the database and 5200 systems, of which 473 have been critically evaluated. The database has over 1800 references.

This is a database of total ionization cross sections of atoms and molecules by electron impact. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included. Singly differential cross sections are included for H, He, and H2. Electron-impact excitation cross sections are also included for selected atoms.

This page, "Benzil monohydrazone", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

FLYCHK provides a capability to generate atomic level populations and charge state distributions for low-Z to mid-Z elements under NLTE conditions.