The dependence on wavelength of ¹³C isotope effects in photolysis of aqueous solutions of ferrie oxalate

Abstract

The formation of carbon dioxide by photolysis of aqueous solutions of ferric oxalate is accompanied by carbon isotopic fractionation. 12C appears preferentially in the evolved CO2, but the isotope effect depends markedly on the wavelength of the light used. Fractionation is essentially zero (k12/k13 = 1.001) at 366 nm, and increases with wavelength, reaching 1.050 at 520 nm. It is proposed that this variation of isotopic discrimination arises from the differing properties of the excited levels formed by photochemical activation.

Transient Structures and Kinetics of the Ferrioxalate Redox Reaction Studied by Time-Resolved EXAFS, Optical Spectroscopy, and DFT

“…At such a higher excitation state, it may be possible that electron transfer or spin crossover might be more-dominant than dissociation. The 13 C isotope effect has been observed in the 366−520 nm range and is found to depend remarkably on the excitation energy . This isotope is not found in the shorter than 366 nm region.…”

“…Photochemistry of Ferrioxalate. Since Draper suggested that the Fe(III) to Fe(II) redox reaction may find applications in photometry, the redox reaction of ferrioxalate solution has been studied widely. − The ferrioxalate redox reaction has also been used as a precise actinometer, and its photochemistry has been studied by several techniques including flash photolysis and electroanalysis. ,,, It is generally accepted 4-7 that light induces electron transfer that reduces the Fe(III)(C 2 O 4 ) complex to the Fe(II) complex with the overall photoreaction written as: 5 …”

Evaluation of Transboundary Secondary Organic Aerosol in the Urban Air of Western Japan: Direct Comparison of Two Site Observations

“…The systematic increase of δ 13 C values with f 44 is strong evidence for the cumulative SOA associating with precursor oxidation found by laboratory studies. 22−24 The more conversion of volatile organic compounds (VOCs) to particulate carboxylate increases f 44 and 13 C content in the product phase, such as SOA. Such a systematic trend was first observed in ambient measurements of δ 13 C values of LV-WSOC at a background site 7 but not in the urban site.…”

“…The different δ 13 C values between the two sites may be explained by the addition of local LV-WSOC with different δ 13 C at Fukuoka. Isotope fractionation(s) accompanied by different chemical reactions in the condensed phase of LV-WSOC at Fukuoka cannot be the explanation for this shift because the chemical reactions resulting in the release of volatile carbonaceous products, such as carbon dioxide, have normal isotope fractionations, − consequently shifting δ 13 C of residual LV-WSOC to a heavier composition. This trend was further investigated using an end-member mixing analysis (EMMA) in subsection .…”

“…Our objective in this study is to better understand the origins of LV-WSOC in the urban air of Fukuoka using δ 13 C and AMS measurements. We conducted simultaneous field measurements in March 2012 and December 2010 at measurement sites in Fukuoka city and Fukue Island in the northern Kyushu region.…”