Déformation photoinduite dans les films minces contenant des ...

Chapter 4. Photomechanical response of hybrid metal/azo-polymer layered structures123!""#"$"%&'"(10 x 10 !mEDCBAdeformation amplitude (nm)15105P-250s-4Vdepth_4V_dots_1beamdepth_4V_line_2beamdepth_4V_line_1beamdepth_2V_line_2beamstip-sample_interactions sg-dr1pastel-00527388, version 1 - 19 Oct 20100100 50 100 150 200 250 3000exposure time (s)0 1 2 3 4 5 6 7!mA B C D EFigure 4.6: Apertureless near-field photomechanical effects in a 200 nm thick sol-gelSi-DR1 film: the tip-to-sample depth_4V_dots_1beam distance corresponds to a shear-force set-point of 4V .depth_4V_line_2beamFive different exposure timestip-sample_interactions sg-dr1depth_4V_line_1beamhave been used: τ exp = A: 200 s, B:100 s, C:50 s, D:20depth_2V_line_2beamss, E: 13 s. The sample is illuminated with a p-polarized single beam of wavelengthλ = 473 nm and of power density 1 mW/mm 2 the incidence angle is θ = 16.5 ◦ .304.2.1 Apertureless near-field photomechanical response of an uncoateddeformation amplitude (nm)25azobenzene-containing thin film20single beam, 4V, scan offBefore studying the near-field photomechanical response of the hybrid metal/azo-polymersingle beam, 4V, scan onlayered structures we have 15 measured the near-field photodeformation of the 2 beams, uncoated 4V, scan onphotochromic films when using our optical fiber tip as apertureless light 2 nano-source.beams, 2V, scan onWe expect to observe a less 10 efficient effect with a glass tip with respect to what previouslyreported with metallized tips [5], which are known to exhibit enhanced near-field5effects.0t exp (s) 0 100 200 300 400 500 600 7004.2.1.1 Deformation induced in the tip near-field under uniform illumination4V2Vtip-sample interaction (V)exposure time (s)scan off scan onIn Figure 4.6 we show 5 dots (A-E), separated one another by 1.2 µm. Each dot hasbeen obtained by keeping the tip in the same position during illumination with a singlep-polarized beam (1 mW/mm 2 ). The tip-to-sample shear-force interaction amplitudeis measured at the lock-in output signal and is kept constant by choosing the set-pointthrough the gain G C (Figure 4.5) 2 . In the present experiment, the set-point was2 For more details see Chapter 2.