TY - JOUR
T1 - Circular polarization in scattered light as a possible biomarker
AU - Sparks, W.
AU - Hough, J.
AU - Kolokolova, L.
AU - Germer, T.A.
AU - Chen, F.
AU - DasSarma, S.
AU - DasSarma, P.
AU - Robb, F.T.
AU - Manset, N.
AU - Reid, I.
AU - Macchetto, F.D.
AU - Martin, W.
N1 - Original article can be found at : http://www.sciencedirect.com/ Copyright Elsevier
PY - 2009
Y1 - 2009
N2 - Biological molecules exhibit homochirality and are optically active. Therefore, it is possible that the scattering of light by biological molecules might result in a macroscopic signature in the form of circular polarization. If this is the case, then circular polarization spectroscopy, which may be utilized in remote sensing, can offer a powerful indicator of the presence of a universal biosignature, namely homochirality. Here, we describe laboratory experiments designed to investigate this idea. We focus on photosynthetic microorganisms, and also show results from macroscopic vegetation and control minerals. In the microorganisms, we find unambiguous circular polarization associated with electronic absorption bands of the photosynthetic apparatus. Macroscopic vegetation yields a stronger and more complex signature while the control minerals produce low-levels of circular polarization unrelated to their spectra. We propose a heuristic explanation of our results, which is that the polarization is produced by circular dichroism in the material after the light has undergone its last scattering event. The results are encouraging for the use of circular polarization spectroscopy in remote sensing of a generic biomarker from space or the ground.
AB - Biological molecules exhibit homochirality and are optically active. Therefore, it is possible that the scattering of light by biological molecules might result in a macroscopic signature in the form of circular polarization. If this is the case, then circular polarization spectroscopy, which may be utilized in remote sensing, can offer a powerful indicator of the presence of a universal biosignature, namely homochirality. Here, we describe laboratory experiments designed to investigate this idea. We focus on photosynthetic microorganisms, and also show results from macroscopic vegetation and control minerals. In the microorganisms, we find unambiguous circular polarization associated with electronic absorption bands of the photosynthetic apparatus. Macroscopic vegetation yields a stronger and more complex signature while the control minerals produce low-levels of circular polarization unrelated to their spectra. We propose a heuristic explanation of our results, which is that the polarization is produced by circular dichroism in the material after the light has undergone its last scattering event. The results are encouraging for the use of circular polarization spectroscopy in remote sensing of a generic biomarker from space or the ground.
KW - circular polarization
KW - biomarker
KW - astrobiology
U2 - 10.1016/j.jqsrt.2009.02.028
DO - 10.1016/j.jqsrt.2009.02.028
M3 - Article
SN - 0022-4073
VL - 110
SP - 1771
EP - 1779
JO - Journal of Quantitative Spectroscopy and Radiative Transfer
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
IS - 14-16
ER -