Vibrational relaxation pathways of AI and AII modes in N-methylacetamide clusters.

Content Provider	Semantic Scholar
Author	Piatkowski, Lukasz Bakker, Huib J.
Copyright Year	2010
Abstract	We studied the pathways of vibrational energy relaxation of the amide I (~1660 cm⁻¹) and amide II (~1560 cm⁻¹) vibrational modes of N-methylacetamide (NMA) in CCl₄ solution using two-color femtosecond vibrational spectroscopy. We measured the transient spectral dynamics upon excitation of each of these amide modes. The results show that there is no energy transfer between the amide I (AI) and amide II (AII) modes. Instead we find that the vibrational energy is transferred on a picosecond time scale to a common combination tone of lower-frequency modes. By use of polarization-resolved femtosecond pump-probe measurements we also study the reorientation dynamics of the NMA molecules and the relative angle between the transition dipole moments of the AI and AII vibrations. The spectral dynamics at later times after the excitation (>40 ps) reveal the presence of a dissociation process of the NMA aggregates, trimers, and higher order structures into dimers and monomers. By measuring the dissociation kinetics at different temperatures, we determined the activation energy of this dissociation E(a) = 35 ± 3 kJ mol⁻¹.
File Format	PDF HTM / HTML
DOI	10.1021/jp107590b
PubMed reference number	20942502
Journal	Medline
Volume Number	114
Issue Number	43
Alternate Webpage(s)	https://request.pub.amolf.nl/request?att_id=15618M_Piatkowsk.pdf
Journal	The journal of physical chemistry. A
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article