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X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study.

Inkinen J, Niskanen J, Talka T, Sahle CJ, Müller H, Khriachtchev L, Hashemi J, Akbari A, Hakala M, Huotari S - Sci Rep (2015)

Bottom Line: We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects.The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light.Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Helsinki, Finland.

ABSTRACT
A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

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Related in: MedlinePlus

The time-resolved carbon core-electron excitation spectra from the experiment.(a,b) The spectra of the CA and TA samples, respectively, after the X-ray irradiation times as shown. The isosbestic points in the TA spectra series are marked with circles. (c) Comparisons of the spectra of the CA and TA samples at selected times.
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f2: The time-resolved carbon core-electron excitation spectra from the experiment.(a,b) The spectra of the CA and TA samples, respectively, after the X-ray irradiation times as shown. The isosbestic points in the TA spectra series are marked with circles. (c) Comparisons of the spectra of the CA and TA samples at selected times.

Mentions: The time-evolution of the carbon core-electron excitation spectra measured from the crystalline samples of α-trans-cinnamic and α-truxillic acid are displayed in Fig. 2 panels (a) and (b), respectively. These spectra are from here on referred to as the CA and TA spectra. The beginning of the X-ray irradiation of the samples corresponds to the origin of the time-scales (0–196 min and 0–375 min). The spectra are normalized to unit area in the energy range 282–296 eV.


X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study.

Inkinen J, Niskanen J, Talka T, Sahle CJ, Müller H, Khriachtchev L, Hashemi J, Akbari A, Hakala M, Huotari S - Sci Rep (2015)

The time-resolved carbon core-electron excitation spectra from the experiment.(a,b) The spectra of the CA and TA samples, respectively, after the X-ray irradiation times as shown. The isosbestic points in the TA spectra series are marked with circles. (c) Comparisons of the spectra of the CA and TA samples at selected times.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644965&req=5

f2: The time-resolved carbon core-electron excitation spectra from the experiment.(a,b) The spectra of the CA and TA samples, respectively, after the X-ray irradiation times as shown. The isosbestic points in the TA spectra series are marked with circles. (c) Comparisons of the spectra of the CA and TA samples at selected times.
Mentions: The time-evolution of the carbon core-electron excitation spectra measured from the crystalline samples of α-trans-cinnamic and α-truxillic acid are displayed in Fig. 2 panels (a) and (b), respectively. These spectra are from here on referred to as the CA and TA spectra. The beginning of the X-ray irradiation of the samples corresponds to the origin of the time-scales (0–196 min and 0–375 min). The spectra are normalized to unit area in the energy range 282–296 eV.

Bottom Line: We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects.The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light.Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Helsinki, Finland.

ABSTRACT
A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

No MeSH data available.


Related in: MedlinePlus