Optical oscillator strength distribution of amino acids from 3 to 250eV and examination of the Thomas–Reiche–Kuhn sum rule

Kamohara, Masumi; Izumi, Yudai; Tanaka, Masafumi; Okamoto, K.; Tanaka, Masahito; Kaneko, Fusae; Kodama, Yoko; Koketsu, Toshiyuki; Nakagawa, Kazumichi

doi:10.1016/j.radphyschem.2008.05.010

Cited by 16 publications

(23 citation statements)

References 3 publications

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“…Optical absorption spectra of LL are shown in Fig. 3, where the spectrum of L-Ala has been reproduced from Kamohara et al (2008). The optical absorption cross-section of L-Ala σ L (l) at l=172 nm was 2.1×10 −17 cm 2 and half as large as the σ LL (l) at l=172 nm.…”

Section: Optical Absorption Cross Section Of Llmentioning

confidence: 98%

“…The thickness of film was estimated to be about 300 nm. Because an L-Ala film with a thickness of 300 nm absorbs 99% of incident photons with an energy of 7.2 eV (Kamohara et al 2008), desorption from the Pyrex glass plate was ignored.…”

Section: Mass Spectral Measurement Of Desorbed Moleculesmentioning

confidence: 99%

“…Racemization occurs because a radical including an α-carbon is planar, so another radical Wavelength λ / nm LL 172 nm 7.2 eV L-Ala (Kamohara et al, 2008) Fig. 3 Absorption spectra of L-alanyl-L-alanine (LL) and L-alanine (Ala) (Kamohara et al 2008) can attack it with equal probability from above or below. It is more difficult for radicals to move around in solid films than in aqueous solution, so stable radicals including an α-carbon would be necessary for racemization in a solid film.…”

Section: Racemization Of L-alamentioning

confidence: 99%

“…Figure 4 shows the experimental results of decomposition of L-Ala and the corresponding calculated line of best fit. The quantum yield f 1 of L-Ala decomposition was determined to be (8.2±0.7)×10 −2 photon −1 from the line of best fit, s L ¼ 2:1 Â 10 À17 cm 2 (Kamohara et al 2008) and p ¼ 5:4 Â 10 15 photons cm −2 s −1 .…”

Section: Quantum Yieldmentioning

confidence: 99%

“…The line of best fit curve has an inflection point, namely [LL]/[L] 0 increased for 39 s and then decreased. The quantum yields f 2 of LL production and f 3 of LL decomposition were determined to be (1.2±0.3)× 10 −3 photon −1 and 0.24±0.06 photon −1 , respectively, from the line of best fit, where s L ¼ 2:1 Â 10 À17 cm 2 (Kamohara et al 2008), s LL ¼ 4:2 Â 10 À17 cm 2 and p ¼ 5:4 Â 10 15 photons cm −2 s −1 . Because we determined the quantum yields of L-Ala decomposition, LL production and LL decomposition, we can determine the half-life of L-Ala and inflection point of [LL]/[L] 0 when irradiated with stellar VUV radiation with an energy of 7.2 eV.…”

Section: Quantum Yieldmentioning

confidence: 99%

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Quantum Yields of Decomposition and Homo-Dimerization of Solid L-Alanine Induced by 7.2 eV Vacuum Ultraviolet Light Irradiation: An Estimate of the Half-Life of L-Alanine on the Surface of Space Objects

Izumi

Nakagawa

2011

Orig Life Evol Biosph

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One of the leading hypotheses regarding the origin of prebiotic molecules on primitive Earth is that they formed from inorganic molecules in extraterrestrial environments and were delivered by meteorites, space dust and comets. To evaluate the availability of extraterrestrial amino acids, it is necessary to examine their decomposition and oligomerization rates as induced by extraterrestrial energy sources, such as vacuum ultraviolet (VUV) and X-ray photons and high energy particles. This paper reports the quantum yields of decomposition ((8.2 ± 0.7) × 10(-2) photon(-1)) and homo-dimerization ((1.2 ± 0.3) × 10(-3) photon(-1)) and decomposition of the dimer (0.24 ± 0.06 photon(-1)) of solid L-alanine (Ala) induced by VUV light with an energy of 7.2 eV. Using these quantum yields, the half-life of L-Ala on the surface of a space object in the present earth orbit was estimated to be about 52 days, even when only photons with an energy of 7.2 eV emitted from the present Sun were considered. The actual half-life of solid L-Ala on the surface of a space object orbit around the present day Earth would certainly be much shorter than our estimate, because of the added effect of photons and particles of other energies. Thus, we propose that L-Ala needs to be shielded from solar VUV in protected environments, such as the interior of a meteorite, within a time scale of days after synthesis to ensure its arrival on the primitive Earth.

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Section: Optical Absorption Cross Section Of Llmentioning

confidence: 98%

Section: Mass Spectral Measurement Of Desorbed Moleculesmentioning

confidence: 99%