S-1 Electronic Supplementary Information An insight into the molecular and surface state photoluminescence of carbon dots revealed through solvent induced modulations in their excitation wavelength dependent emission properties Poojan Milan Gharat, a Jiddhu M. Chethodil, b Amit P. Srivastava, c Praseetha P. K., b Haridas Pal, a,d and Sharmistha Dutta Choudhury* a,d a Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India E-mail: sharmidc@barc.gov.in b Department of Nanotechnology, Noorul Islam Centre for Higher Education, Kumaracoil, Kanyakumari District, Tamil Nadu, 629180 c Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085, India. d Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India Note S1: Synthesis of the Carbon dots (LD1 and LD2) The two kinds of carbon dots used in the present study were synthesized directly from freshly squeezed lemon juice, a natural bioresource, by simple one-step thermolysis reaction at two different temperature conditions. 1 Based on the raw material used (Citrus limon), the obtained carbon dots are referred as LD1 and LD2. For LD1, 25 ml of filtered lemon juice was taken in a glass beaker and heated at 100°C for 90 minutes, till the colour of the sample changed to orange brown. The liquid was then centrifuged for 30 minutes at 10000 rpm. The resulting supernatant was further filtered using Whatman filter paper and the filtrate containing LD1 suspension was stored in a refrigerator for further use. Electronic Supplementary Material (ESI) for Photochemical & Photobiological Sciences. This journal is © The Royal Society of Chemistry and Owner Societies 2018