DÃ©formation photoinduite dans les films minces contenant des ...

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Chapter 4. Photomechanical response of hybrid metal/azo-polymer layered structures122scanpiezozditherpiezoshear-forcemeasureV in!""#$%&'(optical fiber tippastel-00527388, version 1 - 19 Oct 2010filmsubstrate!laser beamszyxV C1/G c+ -eV inG CRHT gainlock-inzscanpiezoditherpiezoFigure 4.5: Tip-sample interactions: experimental setup. Dither piezo: shear-forcemeasurement; (x, y, x) scan piezo: displacement.4.2 Near-field photomechanical response of hybridmetal/azo-polymer layered structuresIn section 3.4.5 we have seen that, in photochromic thin films, near-field irradiation,either in the case of illumination through a small aperture tip [2, 3] or with an aperturelessSNOM tip [4], induces matter accumulation under the light nano-source, where theintensity of the ⃗ E ⊥ field component is preponderant. This is coherent with several otherobservations, under far-field irradiation, of matter accumulation towards the ⃗ E ⊥ fieldcomponents and away from ⃗ E ‖ . However, the interpretation of the near-field photomechanicalresponse of photochromic thin films does not take into account the possiblemechanical interaction between the tip and the surface.In this section we present photodeformation phenomena observed in hybrid metal/azopolymerlayered structures in the presence of a near-field probe. We will show thatthe photoinduced pattern is completely different from the deformation obtained on anuncoated photochromic film and that the interactions between the local probe and themetallic surface play a predominant role in the deformation process.
Chapter 4. Photomechanical response of hybrid metal/azo-polymer layered structures123!""#"$"%&'"(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.
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Thèse de doctorat de l’Ecole Pol
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AcknowledgementsAt the beginning it
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vpastel-00527388, version 1 - 19 Oc
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ContentsAbstractiAcknowledgementsii
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List of Figures1.1 The trans/cis ph
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List of Figuresxiipastel-00527388,
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pastel-00527388, version 1 - 19 Oct
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pastel-00527388, version 1 - 19 Oct
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Introduction 2In this work, we stud
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Bibliography[1] A. Natansohn, P. Ro
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Introduction 6azobenzene-containing
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"##$%&'()')*#'+(%,-.(/#'011'2'"(%)(
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Chapter 1. The azobenzene molecules
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Chapter 2. Experimental setup and s
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pmma-dr1Chapter 2. Experimental set
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Chapter 3pastel-00527388, version 1
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Chapter 3. Microscopic mechanisms a
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dose (mJ!mm )(a)dose (mJ!mm )(b)dos
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Page 88 and 89: Chapter 3. Microscopic mechanisms a
Page 98 and 99: TOPOGRAPHYgratamplxxphotoexpansion
Page 120 and 121: pmmaChapter 3. Microscopic mechanis
Page 132 and 133: Chapter 4. Photomechanical response
Page 134 and 135: sg+goldChapter 4. Photomechanical r
Page 140 and 141: P-250s-4VChapter 4. Photomechanical
Page 146 and 147: P-250s-4VChapter 4. Photomechanical
Page 152 and 153: Chapter 5Nanostructured hybrid syst
Page 154 and 155: Chapter 5. Nanostructured hybrid sy
Page 166 and 167: Bibliography[1] A. Natansohn, P. Ro
Page 168 and 169: Conclusionspastel-00527388, version
Page 170 and 171: Bibliography[1] Chi-Ming Che et Al.
Page 172 and 173: Appendix A 156⎛ ⎞ ⎛n g sinθ
Page 174 and 175: Appendix A 158hence for each compon
Page 176 and 177: Appendix BPhotoisomerization dynami
Page 178 and 179: Appendix B 162( 1Since λ 2 = −(
Page 180 and 181: Appendix C 164L = 5000 nmu = 1 nmL!
Page 182 and 183: Appendix D 166n. light power densit
Page 184 and 185: Bibliography[1] A. Natansohn, P. Ro
Page 186 and 187: Bibliography 170azobenzene-containi
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Bibliography 172as estimated from a
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Bibliography 174[53] C. Barrett, A.
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