TY - JOUR
T1 - Effect of Hydrogen Bonds on the Vibrational Relaxation and Orientational Relaxation Dynamics of HN3 and N3- in Solutions
AU - Lee, Chiho
AU - Son, Hyewon
AU - Park, Sungnam
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MEST) (Nos. 2016R1A2B4011522 and 20100020209). IRpump-probe experiments were performed at the Korea BasicScience Institute (KBSI), Seoul Center
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/9/15
Y1 - 2016/9/15
N2 - Hydrogen bonds (H-bonds) play an important role in determining the structures and dynamics of molecular systems. In this work, we investigated the effect of H-bonds on the vibrational population relaxation and orientational relaxation dynamics of HN3 and N3- in methanol (CH3OH) and N,N-dimethyl sulfoxide (DMSO) using polarization-controlled infrared pump-probe spectroscopy and quantum chemical calculations. Our detailed analysis of experimental and computational results reveals that both vibrational population relaxation and orientational relaxation dynamics of HN3 and N3- in CH3OH and DMSO are substantially dependent on the strength of the H-bonds between the probing solute and its surrounding solvent. Especially in the case of N3- in CH3OH, the vibrational population relaxation of N3- is found to occur by a direct intermolecular vibrational energy transfer to CH3OH due to large vibrational coupling strength. The orientational relaxation dynamics of HN3 and N3-, which are well fit by a biexponential function, are analyzed by the wobbling-in-a-cone model and extended Debye-Stokes-Einstein equation. Depending on the intermolecular interactions, the slow overall orientational relaxation occurs under slip, stick, and superstick boundary conditions. For HN3 and N3- in CH3OH and DMSO, the vibrational population relaxation becomes faster but the orientational relaxation becomes slower as the H-bond strength is increased. Our current results imply that H-bonds have significant effects on the vibrational population relaxation and orientational relaxation dynamics of a small solute whose size is comparable to the size of the solvent.
AB - Hydrogen bonds (H-bonds) play an important role in determining the structures and dynamics of molecular systems. In this work, we investigated the effect of H-bonds on the vibrational population relaxation and orientational relaxation dynamics of HN3 and N3- in methanol (CH3OH) and N,N-dimethyl sulfoxide (DMSO) using polarization-controlled infrared pump-probe spectroscopy and quantum chemical calculations. Our detailed analysis of experimental and computational results reveals that both vibrational population relaxation and orientational relaxation dynamics of HN3 and N3- in CH3OH and DMSO are substantially dependent on the strength of the H-bonds between the probing solute and its surrounding solvent. Especially in the case of N3- in CH3OH, the vibrational population relaxation of N3- is found to occur by a direct intermolecular vibrational energy transfer to CH3OH due to large vibrational coupling strength. The orientational relaxation dynamics of HN3 and N3-, which are well fit by a biexponential function, are analyzed by the wobbling-in-a-cone model and extended Debye-Stokes-Einstein equation. Depending on the intermolecular interactions, the slow overall orientational relaxation occurs under slip, stick, and superstick boundary conditions. For HN3 and N3- in CH3OH and DMSO, the vibrational population relaxation becomes faster but the orientational relaxation becomes slower as the H-bond strength is increased. Our current results imply that H-bonds have significant effects on the vibrational population relaxation and orientational relaxation dynamics of a small solute whose size is comparable to the size of the solvent.
UR - http://www.scopus.com/inward/record.url?scp=84987792287&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.6b06239
DO - 10.1021/acs.jpcb.6b06239
M3 - Article
AN - SCOPUS:84987792287
SN - 1520-6106
VL - 120
SP - 9723
EP - 9731
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 36
ER -