NASA Ames PAH IR Spectroscopic Database

Transitions

ν_k [cm^-1]	λ [μm]	int [km/mol]
3757	2.662	147
1624	6.158	167
1587	6.301	196
1508	6.631	121
1456	6.868	101
1430	6.993	110
1409	7.097	332
1394	7.174	924
1370	7.299	147
1365	7.326	294
1357	7.369	440
1352	7.396	206
1348	7.418	889
1334	7.496	137
1326	7.541	231
1309	7.639	1.04e+3
1274	7.849	121
1258	7.949	107
1247	8.019	60.9
1208	8.278	47.1
1183	8.453	255
1170	8.547	84.8
1163	8.598	13.8
1142	8.757	35.3
1109	9.017	17
1036	9.653	23
992	10.08	32.8
885	11.3	68.8
816	12.25	28.4
797	12.55	35.8
786	12.72	72.4
764	13.09	238
751	13.32	154
734	13.62	387
720	13.89	348
717	13.95	365
706	14.16	219
692	14.45	216
646	15.48	11.6
615	16.26	28.7
588	17.01	264
576	17.36	154
508	19.69	31.4

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[hi,wx]heptacene or naptho-anthraceno-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