TY - JOUR
T1 - Size-dependent fluorescence of bioaerosols
T2 - Mathematical model using fluorescing and absorbing molecules in bacteria
AU - Hill, Steven C.
AU - Williamson, Chatt C.
AU - Doughty, David C.
AU - Pan, Yong Le
AU - Santarpia, Joshua L.
AU - Hill, Hanna H.
PY - 2015/5/1
Y1 - 2015/5/1
N2 - This paper uses a mathematical model of fluorescent biological particles composed of bacteria and/or proteins (mostly as in Hill et al., 2013 [23]) to investigate the size-dependence of the total fluorescence emitted in all directions. The model applies to particles which have negligible reabsorption of fluorescence within the particle. The specific particles modeled here are composed of ovalbumin and of a generic Bacillus. The particles need not be spherical, and in some cases need not be homogeneous. However, the results calculated in this paper are for spherical homogeneous particles. Light absorbing and fluorescing molecules included in the model are amino acids, nucleic acids, and several coenzymes. Here the excitation wavelength is 266nm. The emission range, 300 to 370nm, encompasses the fluorescence of tryptophan. The fluorescence cross section (CF) is calculated and compared with one set of published measured values. We investigate power law (Ady) approximations to CF, where d is diameter, and A and y are parameters adjusted to fit the data, and examine how y varies with d and composition, including the fraction as water. The particle[U+05F3]s fluorescence efficiency (QF=CF/geometric-cross-section) can be written for homogeneous particles as QabsRF, where Qabs is the absorption efficiency, and RF, the fraction of the absorbed light emitted as fluorescence, is independent of size and shape. When QF is plotted vs. mid or mi(mr-1)d, where m=mr+imi is the complex refractive index, the plots for different fractions of water in the particle tend to overlap.
AB - This paper uses a mathematical model of fluorescent biological particles composed of bacteria and/or proteins (mostly as in Hill et al., 2013 [23]) to investigate the size-dependence of the total fluorescence emitted in all directions. The model applies to particles which have negligible reabsorption of fluorescence within the particle. The specific particles modeled here are composed of ovalbumin and of a generic Bacillus. The particles need not be spherical, and in some cases need not be homogeneous. However, the results calculated in this paper are for spherical homogeneous particles. Light absorbing and fluorescing molecules included in the model are amino acids, nucleic acids, and several coenzymes. Here the excitation wavelength is 266nm. The emission range, 300 to 370nm, encompasses the fluorescence of tryptophan. The fluorescence cross section (CF) is calculated and compared with one set of published measured values. We investigate power law (Ady) approximations to CF, where d is diameter, and A and y are parameters adjusted to fit the data, and examine how y varies with d and composition, including the fraction as water. The particle[U+05F3]s fluorescence efficiency (QF=CF/geometric-cross-section) can be written for homogeneous particles as QabsRF, where Qabs is the absorption efficiency, and RF, the fraction of the absorbed light emitted as fluorescence, is independent of size and shape. When QF is plotted vs. mid or mi(mr-1)d, where m=mr+imi is the complex refractive index, the plots for different fractions of water in the particle tend to overlap.
KW - Aerosol characterization
KW - Bioaerosols
KW - Fluorescence
KW - Light scattering
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U2 - 10.1016/j.jqsrt.2015.01.011
DO - 10.1016/j.jqsrt.2015.01.011
M3 - Article
AN - SCOPUS:84923364465
VL - 157
SP - 54
EP - 70
JO - Journal of Quantitative Spectroscopy and Radiative Transfer
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
SN - 0022-4073
ER -