TY - JOUR
T1 - Bulk viscosity of CO2 from Rayleigh-Brillouin light scattering spectroscopy at 532 nm
AU - Wang, Yuanqing
AU - Ubachs, Wim
AU - Van De Water, Willem
PY - 2019
Y1 - 2019
N2 -
Rayleigh-Brillouin scattering spectra of CO
2
were measured at pressures ranging from 0.5 to 4 bars and temperatures from 257 to 355 K using green laser light (wavelength 532 nm, scattering angle of 55.7°). These spectra were compared to two line shape models, which take the bulk viscosity as a parameter. One model applies to the kinetic regime, i.e., low pressures, while the second model uses the continuum, hydrodynamic approach and takes the rotational relaxation time as a parameter, which translates into the bulk viscosity. We do not find a significant dependence of the bulk viscosity with pressure or temperature. At pressures where both models apply, we find a consistent value of the ratio of bulk viscosity over shear viscosity η
b
/η
s
= 0.41 ± 0.10. This value is four orders of magnitude smaller than the common value that is based on the damping of ultrasound and signifies that in light scattering only relaxation of rotational modes matters, while vibrational modes remain "frozen."
AB -
Rayleigh-Brillouin scattering spectra of CO
2
were measured at pressures ranging from 0.5 to 4 bars and temperatures from 257 to 355 K using green laser light (wavelength 532 nm, scattering angle of 55.7°). These spectra were compared to two line shape models, which take the bulk viscosity as a parameter. One model applies to the kinetic regime, i.e., low pressures, while the second model uses the continuum, hydrodynamic approach and takes the rotational relaxation time as a parameter, which translates into the bulk viscosity. We do not find a significant dependence of the bulk viscosity with pressure or temperature. At pressures where both models apply, we find a consistent value of the ratio of bulk viscosity over shear viscosity η
b
/η
s
= 0.41 ± 0.10. This value is four orders of magnitude smaller than the common value that is based on the damping of ultrasound and signifies that in light scattering only relaxation of rotational modes matters, while vibrational modes remain "frozen."
UR - http://www.scopus.com/inward/record.url?scp=85064601940&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:85064601940
SN - 0021-9606
VL - 150
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 15
M1 - 154502
ER -