NASA Ames PAH IR Spectroscopic Database

Transitions

ν_k [cm^-1]	λ [μm]	int [km/mol]
4903	2.04	8.85e+3
3165	3.159	62.1
2950	3.389	166
2814	3.554	100
2798	3.574	144
2777	3.601	199
2678	3.734	140
2666	3.752	103
2639	3.789	13.8
2615	3.824	120
2577	3.88	38
2567	3.895	44
1585	6.31	56.9
1571	6.367	74.3
1556	6.429	292
1530	6.536	49.1
1508	6.63	369
1466	6.821	316
1415	7.067	252
1402	7.135	24.3
1383	7.23	26.7
1370	7.298	545
1365	7.325	909
1357	7.37	898
1330	7.52	677
1309	7.639	3.03e+3
1198	8.347	31.2
1193	8.384	52.4
1183	8.454	622
1164	8.59	15.8
1036	9.649	92.4
997.1	10.03	13.2
923.4	10.83	40.1
879.5	11.37	21.9
820.7	12.18	18.2
797.3	12.54	63.7
765.8	13.06	34.8
760.8	13.14	24
751.3	13.31	39.1
705.6	14.17	38.1
575.5	17.38	148
508.5	19.67	23.2

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