NASA Ames PAH IR Spectroscopic Database

Transitions

Frequency [wavenumbers]	Wavelength [microns]	Integrated cross-section [km/mol]
3064	3.264	192.6
1931	5.178	6.622
1915	5.221	2.288
1904	5.253	3.431
1789	5.589	11.44
1745	5.73	4.575
1674	5.975	1.144
1634	6.119	6.622
1601	6.247	1.144
1573	6.357	2.288
1543	6.48	1.144
1503	6.652	4.575
1454	6.878	1.144
1448	6.907	1.144
1407	7.106	2.288
1400	7.142	4.575
1350	7.405	7.826
1334	7.493	2.288
1321	7.571	9.03
1299	7.699	27.69
1279	7.82	2.288
1269	7.88	2.288
1221	8.189	1.144
1191	8.396	1.144
1184	8.446	2.288
1164	8.59	2.288
1122	8.912	5.719
1048	9.545	2.288
995.1	10.05	6.622
952.8	10.5	7.826
899.9	11.11	114.4
877.4	11.4	1.144
823.7	12.14	17.46
731.3	13.67	96.32
727	13.76	1.144
623.4	16.04	5.719
570.2	17.54	3.431

Laboratory Spectrum

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This spectrum was measured using the matrix isolation technique. Samples are prepared by co-deposition of the PAH in the gaseous state with an overabundance of argon onto a cold CsI window suspended in a high vacuum chamber (p ~ 10-8 mtorr). The CsI window temperature is held between 10 and 15 K for the duration of the experiment. The infrared spectrum of the cold CsI window is recorded prior to (I₀) and immediately after sample deposition (I_n). The absorbance spectrum for a neutral, matrix isolated PAH is log(I_n/I₀).

By irradiating this matrix with ultraviolet radiation from a microwave powered hydrogen discharge lamp produces ionized PAHs. The infrared spectrum is again measured (I_i), now having absorption bands due to both the neutral and ionized PAH. This absorbance spectrum (log (I/I_i)) is compared with that of the neutral PAH. Most of the new bands produced by ultraviolet irradiation are due to the ionized form of the PAH. See the provided reference for the specific details regarding the data presented here. In some cases a few bands near 1600 cm^-1 may be due to H₂O.

Note(s):

The reported total integrated absorption cross-section for the CH_str band located around 3000 cm^-1 (3.3 μm) was established by disregarding any substructure seen in the band and simply integrating the entire feature, including any close-by bands.
Pentacene

You are kindly asked to consider the following references for citation when using the database:

C.W. Bauschlicher, Jr., A. Ricca, C. Boersma, L.J. Allamandola, "THE NASA AMES PAH IR SPECTROSCOPIC DATABASE: COMPUTATIONAL VERSION 3.00 WITH UPDATED CONTENT AND THE INTRODUCTION OF MULTIPLE SCALING FACTORS", The Astrophysical Journal Supplement Series, 234, 32, 2018 10.3847/1538-4365/aaa019 — BibTeX - RIS
C. Boersma, C.W. Bauschlicher, Jr., A. Ricca, A.L. Mattioda, J. Cami, E. Peeters, F. Sánchez de Armas, G. Puerta Saborido, D.M. Hudgins, and L.J. Allamandola, "THE NASA AMES PAH IR SPECTROSCOPIC DATABASE VERSION 2.00: UPDATED CONTENT, WEBSITE AND ON/OFFLINE TOOLS", The Astrophysical Journal Supplement Series, 211, 8, 2014 10.1088/0067-0049/211/1/8 — BibTeX - RIS
Mattioda, A. L., Hudgins, D. M., Boersma, C., Ricca, A., Peeters, E., Cami, J., Sánchez de Armas, F., Puerta Saborido, G., Bauschlicher, C. W., J., and Allamandola, L. J. "THE NASA AMES PAH IR SPECTROSCOPIC DATABASE: THE LABORATORY SPECTRA", The Astrophysical Journal Supplement Series, 251, 22, 2020 10.3847/1538-4365/abc2c8 — BibTeX - RIS