Supporting Information. Optical Scattering Spectral Thermometry and Refractometry of a Single Gold Nanoparticle under CW laser excitation

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1 Supporting Information Optical Scattering Spectral Thermometry and Refractometry of a Single Gold Nanoparticle under CW laser excitation Kenji Setoura, Daniel Werner, and Shuichi Hashimoto* Department of Optical Science and Technology, The University of Tokushima, Tokushima , Japan. *Corresponding author. hashichem@tokushima-u.ac.jp 1

2 S1 TEM micrographs of Au NPs 200 nm Figure S1 (a) TEM images and corresponding size distribution of as received 100 nm diameter Au NPs (BBI EMGC 100). 100 nm Figure S1 (b) TEM images and corresponding size distribution Au NPs (BBI EMGC 100) after reshaping by irradiating 532 nm ns pulsed lasers (10 Hz, 3 h, ~10 mj cm -2 ). 2

3 Figure S1 (c) Extinction spectra before and after reshaping by laser irradiation together with calculated Mie extinction spectra of (99±4.5) nm Au spheres dispersed in water. 200 nm Figure S1 (d) 150 nm BBI Au NPs (BBI EMGC-150) after 532 nm nanosecond pulsed laser irradiation (10 Hz, 3 h, ~10 mj cm -2 ). Figure S1 (e) Extinction spectra before and after laser irradiation together with calculated Mie spectra of (155 ± 15) nm Au spheres dispersed in water. 3

4 S2. Calculated and experimental n and κ of bulk gold as a function of wavelength at various temperatures (a) (b) 283 K 573 K 843 K 1193 K Figure S2 (a). Values of n (a) and κ (b) of bulk gold as a function of wavelength at various temperatures by calculated using the equations described in the text. (a) (b) Figure S2 (b). Experimental n (a) and κ (b) values of bulk gold as a function of wavelength at different temperatures by Otter (reproduced from ref. 31). 4

5 S3. Calculated transient temperature curves for a CW laser-heated 150 nm gold sphere embedded in glass. Figure S3. Numerical solutions for the time dependent temperature increase of a CW laser-heated 150 nm gold sphere embedded in glass (refractive index: 1.5, thermal conductivity: 1.0 W m 1 K 1 ). The laser power densities are 2.8 (black curve), 6.1 (red curve) and 9.3 mw µm -2 (blue curve). The calculation was made following the equation given in Hashimoto, S.; Werner, D.; Uwada, T. J. Photochem. Photobiol. C: Rev. 2012, 13, 28. S4. Laser-induced scattering spectral changes of a single 150 nm Au NP on irradiation of 488 nm CW laser. scattering intensity [ arb.unit ] Before irradiation After irradiation During Irradiation Figure S4. Single particle scattering spectral changes before (black), during (blue) and after (red) irradiation (peal power density: 2.04 mw µm 2 ). 5

6 S5 Scattering spectral change of a 150 nm diameter Au NP on a glass substrate in air on illumination of 532 nm CW laser light. scattering intensity / arb.unit Before irradiation After irradiation During irradiation Figure S5 (a). Experimental light scattering spectral change of a 150 nm diameter Au NP on a glass substrate in air under the illumination of 4.93 mw µm 2 of 532 nm CW laser light. T / K data points Liquid AuNP LSM HM LNG λ / nm peak power density / mwµm -2 Figure S5 (b). Scattering spectral shift λ of a 150 nm diameter Au NP as a function of laser peak power density (lower scale) or particle temperature (upper scale) for 532 nm CW laser excitation. LSM curve is for a core diameter of 144 nm with shell thickness of 3 nm. 6

7 S6 The calculated spectral peak shift as a function of the temperature of a 150 nm diameter Au NP supported on a glass substrate in air λ / nm T / K Figure S6. The calculated spectral peak shift as a function of the temperature of a 150 nm diameter Au NP supported on a glass substrate in air (effective medium refractive index: 1.12). 7

8 S7 AFM cross sectional profiles of a 100 mn diameter Au NP before and after laser irradiation and corresponding scattering spectral change Before irradiation After irradiarion height / nm distance / nm Figure S7 (a) AFM cross sectional profiles of a 100 mn diameter Au NP supported on a glass substrate in air before and after irradiation of a 532nm CW laser for 5 s laser (8.1 mw µm -2 ). scattering intensity / arb.unit Before irradiation After irradiation Figure S7 (b) Scattering spectral change on irradiation of a 532nm CW laser for 5 s laser (8.1 mw µm -2 ). 8

9 S8. Experimental and calculated scattering spectra of 100 nm Au NP in water and glycerol (a) (b) scattering cross section / m K 351 K 411 K 472 K 533 K scattering intensity 0 mwµm mwµm mwµm mwµm -2 0 (c) (d) 6 scattering cross section / m K 351 K 411 K 472 K scattering intensity 0 mwµm mwµm mwµm mwµm mwµm Figure S8 (a) Calculated temperature-induced scattering spectral shifts of a single 100 nm diameter Au NP supported on a glass substrate in water; (b) experimental spectral peak shifts of a single 100 nm diameter Au NP supported on a glass substrate in water as a function of excitation laser peak power density (particles with original scattering peaks of 596 ± 2 nm were selected); (c) calculated temperature-induced scattering spectral shifts of a single 100 nm diameter Au NP supported on a glass substrate in glycerol; (d) experimental spectral peak shifts of a single 100 nm diameter Au NP supported on a glass substrate in glycerol as a function of excitation laser peak power density (particles with original scattering peaks of 605 ± 1 nm were selected).

10 S9. Temperature-dependent refractive index as a function of temperature in water and glycerol measured at 589 nm. phase transition (573 K) Figure S9 (a). Temperature-dependent refractive index curve of superheated water at 589 nm (reproduced from ref. 44). At 573 K the refractive index drops down due to transformation to vapor phase. The inset shows an expanded view of the n vs. T curve below the phase transition threshold. The curve follows a 2nd-order parabolic function. Figure S9 (b). Refractive index as a function of temperature for glycerol at 589 nm (reproduced from ref. 45). The curve follows a linear function. 10

11 S10 Darkfied image and light scattering spectra demonstrating the formation of photothermal bubble during irradiation after irradiation before irradiation scattering intensity Figure S10 (a) Scattering spectra of 100 nm diameter Au on a glass substrate in water. Red curve represents the spectra ascribable to a bubble generated by the irradiation with a 532 nm CW laser (33 mw µm 2 ). 20 µm Figure S10 (b) Darkfield microscopy image of a bubble (the bright spot in the center) generated by irradiating a 532 nm CW laser light on 100 nm diameter Au NP (33 mw µm 2 ). 11