NASA Ames PAH IR Spectroscopic Database

Transitions

ν_k [cm^-1]	λ [μm]	int [km/mol]
3395	2.945	913
3062	3.266	40
3012	3.32	16.2
2830	3.534	426
2724	3.672	79.7
2665	3.752	114
2635	3.795	270
2601	3.844	101
2360	4.236	6.71e+3
2248	4.449	5.77e+3
2054	4.868	328
2026	4.936	10.9
2006	4.985	114
1982	5.046	7.31
1969	5.078	13
1892	5.285	54.8
1842	5.428	112
1740	5.745	149
1688	5.924	211
1660	6.025	98.4
1514	6.607	1.95e+3
1440	6.944	1.82e+3
1377	7.264	292
1369	7.303	217
1334	7.497	413
1315	7.603	277
1298	7.706	1.1e+3
1258	7.948	133
1211	8.26	3.85e+3
1125	8.891	96.2
1098	9.106	48.8
1083	9.231	86.6
1052	9.503	83.4
1039	9.626	93.6
1029	9.716	64.8
997.8	10.02	55.6
919.1	10.88	5.23e+3
873.5	11.45	6.44e+3
835.1	11.97	766
814.4	12.28	1.72e+3
779.6	12.83	5.02e+3
746.3	13.4	6.72e+3
739.1	13.53	66.4
734.5	13.61	88.6
715.8	13.97	7.11e+3
707	14.14	19
696	14.37	165
656.3	15.24	341
629.7	15.88	37.3
618.4	16.17	358

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,uv]hexacene or dinaptho-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