Search for Species Data by
Note: This search is by molecular weight
based on single (most-abundant) isotope atomic masses.
These weights may vary significantly from molecular
weights based on average atomic masses. The molecular
weights reported elsewhere in this site are based on
average atomic masses.
Please follow the steps below to
conduct your search (Help):
You may search for species based on molecular weight
values in two ways:
- Specify a single value; the system will search for
values within 0.5 units of this value.
- Specify a range. The limits of the range should
be separated by a comma.
Rules for formula restriction (step 2)
(Back to search)
A chemical formula may be entered to restrict the search to
species which match the formula. The manner in which the
formula is interpreted is controlled by two checkboxes below
the formula entry box:
- Allow elements not specified in formula
- When checked, this option indicates that species
containing elements not specified in the formula
will also be matched. For example, a search for
C2 will match all of the species which
contain exactly two carbon atoms and any number of
- Allow more atoms of elements in formula than specified
- This option indicates that species containg more
atoms than specified of a given element will be matched.
For example, a search for HC with only
this option checked will match only hydrocarbons.
- If one or more of the data types are checked,
the search will be restricted to species which
contain at least one of the data types specified.
- If none of the data types are checked, there
will be no restrictions on the search.
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