SUPPLEMENTARY INFORMATION
Fluorescent Muller matrix analysis of a highly scattering turbid media
Soumitra Satapathi,1,#,* Jalpa Soni,2,# and Nirmalya Ghosh,2
1
Department of Materials Science, Indian Association for the Cultivation of
Science, Kolkata, Jadavpur, 700032,West Bengal, India
2
Department of Physical Sciences, Indian Institute of Science Education and Research
(IISER) Kolkata, Mohanpur 741252, West Bengal, India
1. Materials:
Materials:
Chloroform (CHCl3) and anionic surfactant (sodium dodecyl sulphate (SDS) were purchased
from Sigma Aldrich. The donor polymer poly-3-hexyl thiophene (P3HT) was purchased from
Sigma Aldrich.
2. P3HT nanoparticles synthesis:
P3HT (10 mg) was dissolved in the chloroform (CHCl3) (1 mL). The anionic surfactant, SDS in
aqueous dispersion (1 mg/10 mL) was prepared to stabilize the emulsion and 1-propanol was
utilized as the co-surfactant to reduce the surfactant monolayer rigidity. The polymer in CHCl 3
(250 µL) was added to the aqueous major phase (2.5 mL). To ascertain efficient dispersion, the
mixture was sonicated by bath sonication for 5 min. Evaporation of CHCl3 during the sonication
followed by heating at 65 ˚C for 20 min affords a stable aqueous dispersion of the P3HT
nanoparticles.
3. Experimental set-up of Muller Matrix determination:
The experimental system comprises of the 405 nm line of a diode laser (PE.BDL.405.50,
Pegasus, Shanghai, China) as excitation source, a polarization state generator (PSG) unit and a
polarization state analyzer (PSA) unit to generate and analyze the required polarization states and
is coupled to a CCD spectrometer (Shamrock imaging spectrograph, SR-303i-A, ANDOR
technology, USA) for spectrally resolved signal detection (450 nm – 800 nm). The PSG unit
comprises of a fixed linear polarizer (P1, LPVIS100, Thorlabs, USA) in horizontal state,
followed by a rotatable achromatic quarter wave retarder (Q1, WPQ10M-633, Thorlabs, USA)
mounted on a computer controlled rotational mount (PR<1/M-27E, Thorlabs, USA). The
sample-scattered light, collected and collimated using an assembly of lenses, then passes through
the PSA unit, and is finally recorded using a spectrograph. The PSA unit consists of a similar
arrangement of fixed linear polarizer (P2, at vertical position) and a rotatable achromatic quarter
wave retarder (Q2), but positioned in a reverse order. The fluorescence spectra (em = 450 – 800
nm) corresponding to the sixteen combinations of the PSG and PSA are recorded by sequentially
changing the orientation of the fast axis of the quarter wave retarders of the PSG unit and that of
the PSA unit, to the four optimized angles 35°, 70°, 105°𝑎𝑛𝑑 140°.11 This method is
independent of the source and detector polarization responses as the polarizers P1 and the
analyzer P2 are always fixed at horizontal and vertical polarization states respectively. Further,
usually spectrometers are associated with complex polarization response (owing to the presence
of grating), which is taken care of in our set-up by fixing the polarizers throughout sixteen
measurements. This is an important advantage of our measurement strategy. Never-the-less,
eigenvalue calibration was also performed to yield the exact nature of the system PSG and PSA
matrices (𝑾() 𝑎𝑛𝑑 𝑨() respectively) and their wavelength response; the details of which can
be found in our earlier report.11 For constructing fluorescence spectroscopic Mueller matrices,
the generator matrix 𝑾() for a fixed excitation wavelength (ex = 405 nm) and analyzer matrix
𝑨() for varying emission wavelengths (em = 450 – 800 nm) are used.