Publisher info - 16.12.2008
© ICBP, ETH Zurich, 2007-

Physical Properties Sources Index: Help


The Physical Properties Sources Index (PPSI) is a tool for finding resources for physico-chemical and other material properties. It is a starting point for queries such as

  • Where does one find a listing of rate constants?
  • Where does precise information on chemical structure (bond lengths, bond angles, torsion angles) of molecules in the gas phase exist?
  • Where do I find the definition of the quadrupole moment?
  • Where are techniques for measurement of viscosity described?

This index does not display the measured values of a physical property of a given compound, for example, values of the dipole moment of water. But it lists the sources that contain the dipole-moment values.


The physical properties can be accessed by way of a an alphabetic list, by searching or navigating them in a thesaurus. They are distinguished into classes or properties:

  • Classes contain subclasses or properties. Normally, no sources with data or definitions are assigned to classes. Classes may point to sources with a description of the measurement method. Example for classes and properties: Spectroscopy (class) > High-Frequency Spectroscopy (class) > NMR Spectroscopy (class) > NMR Spectrum (property) > Chemical Shift (property) > 13C NMR (property).
  • Physical properties point to sources (documents, websites, databases). Normally they are listed at the end of a hierarchy.
  • In addition, physical properties may carry facets that render an aspect more precisely. E.g. the facet "photoionisation" belongig to the property "mass spectrum" indicates that the measured compounds were ionised by way of photoionisation.

Similarly, the chemical systems can be accessed by search or navigation in a thesaurus. They are divided into classes, systems, compounds and chemical elements.


Search for physical properties

Search type Explanations Examples
Simple search for physical properties Searching is possible in all available languages (german, english). Refractive Index
Index of refraction
  If several search strings are entered, Boolean AND is used internally to combine them. AND need not be entered. Other Boolean operators cannot be used. Search strings must be separated by spaces. Magnetogyric ratio
  All search strings are right truncated. Thus the search string electr find electron, electronic as well as electric. Magnet
  The order of search strings is not important, with the exception of combined search of physical properties and chemical systems (see below). Acentric factor =
factor acentric
  Search is case insensitive, i.e. upper- or lowercase letters are not distinguished. Acentric Factor =
acentric factor =
aCentriC FACtor
  @ is used as wildcard for a single character. Gr@y would find Gray or Grey. N@R
  For zero to a number of characters, * can be used, either at the beginning (left truncation) or in the middle of the search string. Vapo*r finds vapor oder vapour. Vapo*r
  The order of the search strings or exact word search may be carried out by placing the search terms within quotation marks. "Heat of Mixing"
  If quotation marks are used, you have to add a * for right truncation if needed. "Equilibrium Constant"*
  Add a = before the search string for exact word match. =energy
  The following stop words will be filtered from search: an, and, das, de, der, des, die, ein, eine, et, für, in, on, the, to, und. If you want to include a stop word in the query, place a = in front of it: =the Atoms =and molecules
Combined search for physical properties and chemical systems If you would like to search phyiscal properties for a given chemical system, use the preposition of to designate the chemical system. PPSI recognizes if a physical property or a chemical was meant, e.g. heat of mixing (property), refractive index (property) of organic compounds (system), index of refraction (property) of organic compounds (system) Refractive index of gases

Search for chemical systems

Search type Explanations Examples
Simple search for chemical systems Searching is possible in all available languages (german, english). Chemical names, sum formula, CAS Registry Numbers (CASRN) and Smiles strings can be specified. Hydrocarbons
  The same search rules hold true as for searching physical properties.  


Display of physical properties

Name of the physical property, synonyms and translations, a definition and commonly used symbols and units according to the IUPAC "Green Book" ("Quantities, Units and Symbols in Physical Chemistry") are given.

Display of assigned sources

Term Explanations
Rank Rank allocated by the Information Center. 1 (green) = most important souce one should consult first, 2 (yellow), 3 (orange) and higher: Additional sources to consult. Sources that contain definitions or descriptions of the measurement procedure only always have rank 10. The following qualities are considered for ranking: Quality and quantity of data, ease of access to source, ease of finding the data and ease of use.
Quality Quality judged by the Information Center. 1 = High quality. Criteria: Measurement done by standard procedures or by standards institutions, critical selection of data by a editorial board, measurement deviations and errors are given, 2 = Normal quality, data can be used, 3 = Minor quality, original source of data unclear, source is outdated.
Quantity Estimated number of data values or compounds.
Rating You can rate a source by dragging the mouse pointer over the stars and submitting the grade with a mouse click.
Source type Data (measured) = "Source contains measured data for given physical property"
Daten (calculated) = "Source contains calculated or predicted data for given physical property"
Definition = "Source contains definition of given physical property"
Method of Measurement = "Source contains description of measurement method"
Prediction = "Source can be used to predict values of given physical property"
System Scope of source on chemical systems

Display of chemical systems

The name of the chemical system, its sum formala, the CAS Registry Number and translations are given.

RSS News Feed

RSS (RDF Site Summary, Rich Site Summary, Really Simple Syndication) is an XML-based format designed for publishing news and messages. In order to use RSS, a special NewsReader software must be installed, which allows subscriptions to news channels. The NewsReader automatically downloads the new messages of subscribed channels at regular intervals. Unread messages are mostly displayed in bold, whereas the read messages in normal script. This means that you stay on top of your interests.

Alternatively, one can use a web-based reader service such as Bloglines or Google Reader.

For Windows we recommend the following NewsReaders: Awasu Personal Edition (free), FeedDemon (shareware) oder SharpReader (free); for Mac OS X: NetNewsWire(free). In some browsers such as Mozilla FireFox, Internet Explorer 7, and Apple Safari 3 the RSS facility is inbuilt.

RSS news feeds are represented by the following symbols:

Various browsers indicate in their address bar by the following symbols if a web site offers RSS feeds:

  • Mozilla Firefox: Live Bookmark Firefox Live Bookmark
  • Safari: Safari RSS Anzeige

Use the following link to subscribe to our RSS feed of new physical and chemical properties: RSS

Recommended update frequency: Daily.

Feedback and suggestions

Is an important physical property, a printed source or a database missing in the PPSI? For feedback and suggestions please contact Dr. Martin Brändle.