NASA Ames PAH IR Spectroscopic Database

Transitions

ν_k [cm^-1]	λ [μm]	int [km/mol]
2520	3.968	504
2350	4.255	146
2251	4.442	159
2026	4.936	53.9
1863	5.368	192
1840	5.435	459
1775	5.634	296
1670	5.988	94.3
1540	6.494	134
1530	6.536	135
1521	6.575	198
1436	6.964	197
1354	7.386	60.8
1289	7.758	232
1265	7.905	17.5
1184	8.446	75.3
1174	8.518	128
1084	9.225	34.9
920	10.87	24.9
915	10.93	23.9
901	11.1	22.4
894	11.19	72.3
881	11.35	1.05e+3
842	11.88	270
831	12.03	125
815	12.27	227
804	12.44	113
794	12.59	64.8
779	12.84	394
762	13.12	291
755	13.25	59.8
747	13.39	424
717	13.95	167
705	14.18	59.8
695	14.39	101
656	15.24	24.4
618	16.18	32.4
612	16.34	74.8
610	16.39	95.8

Laboratory Spectrum

Lab — Left-clk & Shift: drag to zoom; Left-clk + Ctrl: Pan; Right-clk: Reset.

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