NASA Ames PAH IR Spectroscopic Database

Transitions

ν_k [cm^-1]	λ [μm]	int [km/mol]
3777	2.648	49.6
3757	2.662	63.1
3712	2.694	78.9
3574	2.798	15.8
3090	3.236	307
3072	3.255	300
3026	3.305	22.5
1926	5.192	22.5
1856	5.388	20.3
1692	5.91	31.6
1624	6.158	54.1
1608	6.219	65.4
1554	6.435	115
1546	6.468	31.6
1532	6.527	302
1505	6.645	128
1489	6.716	72.1
1472	6.793	38.3
1444	6.925	277
1438	6.954	126
1405	7.117	113
1364	7.331	60.9
1351	7.402	289
1335	7.491	160
1305	7.663	194
1273	7.855	78.9
1260	7.937	81.1
1247	8.019	300
1233	8.11	72.1
1166	8.576	63.1
1120	8.929	27
877	11.4	90.2
831	12.03	81.1
800	12.5	160
794	12.59	63.1
755	13.25	295
753	13.28	92.4
705	14.18	81.1
577	17.33	140

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.
Dibenzo[fg,st]pentacene or benzo-natho-pyrene
This species has known electronic transitions in the IR, see referenced work for details

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

Ricca, A., Boersma, C., Maragkoudakis, A., Roser, J.E., Shannon, M.J., Allamandola, L.J., Bauschlicher Jr., C.W., "THE NASA AMES PAH IR SPECTROSCOPIC DATABASE: COMPUTATIONAL VERSION 4.00, SOFTWARE TOOLS, WEBSITE, AND DOCUMENTATION", The Astrophysical Journal Supplement Series, 282, 7, 2025 10.3847/1538-4365/ae1c38 — 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
Bauschlicher, Jr., C.W., Ricca, A., Boersma, C., Allamandola, L.J., "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
Boersma, C., Bauschlicher, Jr., C.W., Ricca, A., Mattioda, A.L., Cami, J., Peeters, E., Sánchez de Armas, F., Puerta Saborido, G., Hudgins, D.M., Allamandola, L.J., "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