Accessing data

The molecular PAH data is accessed through their associated unique identifiers (UIDs). However, a search-interface is available that allows retrieval of these UIDs through simplified queries. The syntax is identical to that used on the NASA Ames PAH IR Spectroscopic Database website.

IDLPython

uids = pahdb->Search("c<=20 neutral n=2 neutral")

The molecular PAH data contained in the database XML-files consists of four main components:

1. Properties, .e.g, molecular weight, zero point energy, total energy, etc.

2. Vibrational transitions

3. Geometric data

4. Laboratory spectra

The following illustrates how to access these components.

IDLPython

pahdb = OBJ_NEW('AmesPAHdbIDLSuite')

uids = pahdb->Search("c<=20 neutral n=2 neutral")

pahs = pahdb->getSpeciesByUID(uids)

transitions = pahdb->getTransitionsByUID(uids)

geometries = pahdb->getGeometryByUID(uids)

laboratory = pahdb->getLaboratoryByUID(uids)

;; work ...

OBJ_DESTROY,[laboratory, $
             geometries, $
             transitions, $
             pahs, $
             pahdb]

Alternatively, one can access these components through the ‘species’-instance.

IDLPython

pahdb = OBJ_NEW('AmesPAHdbIDLSuite')

pahs = pahdb->getSpeciesByUID( $
       pahdb->Search("c<=20 neutral n=2 neutral"))

transitions = pahs->transitions()

geometries = pahs->geometry()

laboratory = pahs->laboratory()

;; work ...

OBJ_DESTROY,[laboratory, $
             geometries, $
             transitions, $
             pahs, $
             pahdb]