Modern Polymer Spect..

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17E (ir 1, R): (iii) z = 4, t = 1, 18 atoms per unit cell, D: point group, 17A (R) +17B, (ir 11, R) +17B: (ir I, Ri +17Bi (ir 1, Ri. The knowledge of the dispersion curves, of the spectroscopic activity of the k = 0 phonons and their precise frequencies has allowed us to locate the energy gaps, where to expect localized defect modes, and to predict where the activation of the density of states singularities (strong peaks in g(v) with no activity in IR and/or Ranian) due to lack of symmetry because of disorder could generate extra absorption or scattering. Since we take for granted that the actual samples of PVC contain geometrical as well as configurational defects at non-negligible concentrations, calculations were extended [90] with the introduction of: (i) conformational defects as isolated units or as possibly interacting multiple units; and (ii) isolated or possibly interacting configurational defects. Of necessity, when configurational defects are introduced, local conformational distortions must be considered so as to justify the existence of an energetically plausible defect. NET was applied for chains consisting of 200 chemical units (i.e., matrices of 3600 x 3600 were constructed), while IIM was restricted to shorter chains made up by 50 units (900 x 900). The distribution of defects was random and the concentrations ranged from an isolated unit to 8'Yo defects. The construction of the large matrices was made from smaller submatrices associated to each chemical unit in a given conformation or configuration. The detailed algebra and the complete expressions for such submatrices are available in [90] and can be applied to any case of polymers made up by chiral chemical repeat units. The attention was mainly focused on the C-C1 stretching range of the supposedly mostly syndiotactic chain. Polymerization in urea clathrates provides the 'purest' sample of planar syndiotactic PVC [130]. Such a chain shows a large energy gap in the CCl stretching range (-650 to 820 cm-'). It is very likely that defect modes from other structures may generate localized gap modes which may be used as useful structural probes. While we refer to [90] for a thorough analysis of the complex structural situation, in Figures 3-33 and 3-34 we give two examples of the frequency and vibrational displacements for an isolated GG or an isolated isotactic diad defect in a fillly syndiotactic planar zig-zag host chain. It must be noted that gap frequencies are different, but that the vibrational displacements associated to these gap modes involve many chemical units (-20). The complexity of the problem is shown in Figure 3-35 where the density of vibrational states of a realistic model of configurationally disordered PVC is compared with the experimental spectrum. 3.16 Structural Inhomogeneity and Raman Spectroscopy of LAM Modes The problem raised in Section 3.14.1 requires further discussion. From longitudinal accordion motion (LAM) spectroscopy of a variety of fatty acids Vergottin et 211.
160 3 Vibmtioriul Spectra us a Probe of Strircturul Order Scale GG-defect gap mode GG 0.05 0 Figure 3-33. Gap mode (described in terms of total displacements of the atoms) for a GG defect in a syndiotactic PVC chain. Notice that the gap mode is localized over a large section of the chain. Figure 3-34. Gap mode (described in terms of total displacements of atoms) for an isotactic isolated dad. Notice the breadth of the mode which extends over at least 20 carbon atoms.
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Modern Polymer Spectroscopy Edited
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Modern Polymer Spectroscopy Edited
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Preface For unfortunate reasons the
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However, theory and calculations yi
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Contents 1 Two-Dimensional Infrared
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Con ten t~ xi Index 5.2 Force Field
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Contributors M. Del Zoppo Dipartime
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1 Two-Dimensional Infrared (2D IR)
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1.2 Brick~qrorrnrl 3 . Figure 1-3.
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1.0 , Figure 1-6. The in-phtrse and
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1.2 Bcrckgroinizd 7 where AA (i~) i
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1.2 Background 9 1.2.5 Two-Dimensio
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1.3 Bnsic Properties of 20 IR Corre
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2D IR spectrometer coupled with a d
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1.5 Applirtrtions 15 Unlike a dispe
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\ '\ Melliyleiie 1'7- -3000 Posiliv
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11 Amorphous Crystalline ,...." I F
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1.5 Applications 21 / I 1430 Figure
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1.5 Appliccitioiis 23 Methylene Fig
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1.5 Ajqdicrrtions 25 3024 Figure 1-
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1.5 Applicutions 27 Furthermore. th
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1.7 Coizclirsions 29 derived in a s
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1.9 References 31 [9] Colthup, N. B
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2 Segmental Mobility of Liquid Crys
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SRMPLE/DETECTOR e3 ‘retardation
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2.4 Srvuc me-Dependenr Alignment 37
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2.5 Electric Field-Innductid Orirnt
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2.5 Electric Field-nclticetl Orient
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a -@ COWER SRHPLE ._ 2.5 Elec tric
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2.5 Electric Field-Itzduced Orienta
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2.5 Electric Field-IwrElrced Orient
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2.5 Electric Field-Im/irced Orientu
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2.5 Electric Field-Induced Orientli
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2.5 Electric Field-Induced Orientat
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2.5 Electric Field-Induced Orienfat
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2.5 Elrc tric Field-Iiidircwl Orim
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2500 2008 I s00 WRVtNdMRtR CM-I Fig
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-3.6 Aligmient OJ' Side- Clinin Liy
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~ polyester 2.6 Alignnient qf Side-
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I." 0.9 0.8 Figure 2-34. FTlR 0.7 p
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induced alignment of the investigat
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2.7 Orientation oj Liquid Ci:i,stal
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2.7 Orieritation of Liquid Ciysttrl
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0 8 18 16 1 a W u z a m a 0 Ln m Q
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2.7 Orientation oj Liquid Crystals
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2.7 Orientation of Liquid Crjvtals
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2.7 Orientatioiz of Liquid Crystals
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2.8 Conclusions 81 strain. As A0 is
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3. I0 Refcreiice.r 83 [I 71 Hoffina
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2.10 References 85 [92] Wiesner, U.
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t Order/Disorder in Chain Molecules
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onds which hold atoms together thro
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3.2 The Dyriamical Case qf Simll ar
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3.2 The Dyrinniical Case of Sinnll
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3.4 S11or.f- and Loizg-Rcrizye Vibr
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3.4 Slzort- and Loiig-Range Vibrati
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eyularity), e.g., 2. During the pol
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3.5 Towards Lnrger Molecules: From
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3.5 TOIIYW~ Laiyer Molertiles: Fvoi
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3.5 Towmu" Larger Molecules: F~om O
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1700 - CIO --- ca c 22 _- c 12 l l
Page 124 and 125: 3.6 From Dynamics to Vibrational Sp
Page 126 and 127: 3.6 Froin Dynaiiiics to T’ihratio
Page 128 and 129: 3.7 The Case of Isotactic Polypropy
Page 130 and 131: 3.7 The Cuse of Isotactic Polypvop.
Page 132 and 133: 3.8 Density of Vibrational States a
Page 134 and 135: 3.8 Dtvz.sit,v of L’ihrntioizal S
Page 136 and 137: 3.8 Driisity of Vibratioiid StLitrs
Page 138 and 139: 3 9 Mouiiiq ToIvmds Rerrlitv: From
Page 140 and 141: 3.9 Moving Towards Reality: From Or
Page 142 and 143: 3.9 Moving Towards Reality: Froin O
Page 144 and 145: 3.10 Wlmt Do We Learn from Cnlcailc
Page 146 and 147: + 3.11 A Very Siriiple Ccrse: Latti
Page 148 and 149: 3 I1 A Yey) Siiiiple Case: LLittice
Page 150 and 151: 3.11 A Vq> Siiiiplc Crrw: Luttice D
Page 152 and 153: Figure 3-22. Sample eigenvectors in
Page 154 and 155: 3.12 CIS-trans Opening @the Double
Page 156 and 157: 3.13 Defect Modes cis Structtrr.al
Page 158 and 159: 3.13 Defect Mo&s cis Structurcil Pr
Page 160 and 161: 0 3.14 Case Studies N 0 d - Y N o m
Page 162 and 163: 3.14 Case Studies 147 OC 60 58 57.
Page 164 and 165: 3.14 Case Studies 149 GI A V E N U
Page 166 and 167: 3.14 Case Studies 15 1 correspond t
Page 168 and 169: 3.14 Case Studies 153 (I10 + 200) +
Page 170 and 171: 3.14 Case Studies 155 1500 1480 146
Page 172 and 173: 3.14 Case Studies 157 the molecular
Page 176 and 177: 3.16 Stnictural Znlioi~zogeneity an
Page 178 and 179: 3.1 7 Fermi Resonancrs 163 stants.
Page 180 and 181: 3.1 7 Femi Resorinnces 165 2 L 1 29
Page 182 and 183: lowing. The CHl-bending mode 6 [cer
Page 184 and 185: 3.17 Ferini Re.sonrriire.s 169 a Fi
Page 186 and 187: 3. I7 Fernii Resoiiances 17 1 terin
Page 188 and 189: 3.18 Band Broadening and Confonnati
Page 190 and 191: 3.18 Bmd Brourleiziriy md Cmforrnat
Page 192 and 193: 3.18 Band Bvoaderiing arid Conjonna
Page 194 and 195: 3.18 Band Broadening and Confornmti
Page 196 and 197: 3.19 A Worked E.utinple 181 pre-mel
Page 198 and 199: 3.19 A Wovh-ecl E.uanzple 183
Page 200 and 201: 3.19 A Worked Example 185 19 5°C 2
Page 202 and 203: 3.19 A Workrd Example 187 Figure 3-
Page 204 and 205: 3.19 A Worked E.rcnniplr 189 LAM I
Page 206 and 207: 3.19 A Worked E.xuniple 191 Figure
Page 208 and 209: 3.19 A Worked E.vnn~yle 193 Figure
Page 210 and 211: 3.19 A Worked E.vnrqde 195 009.1 00
Page 212 and 213: 3.19 A Worked Example 197 existence
Page 214 and 215: 3.1 9 A Worked Example 199 The soli
Page 216 and 217: 3.20 References 201 very important,
Page 218 and 219: 3.20 References 203 [41] M. Gussoni
Page 220 and 221: 3.20 Refeeveiicrs 205 [I 171 P. Jon
Page 222 and 223: 4 Vibrational Spectroscopy of Intac
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4.3 Georrietvy oj Intuct Po1vniev.r
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1'45 4.4 Geometric Chunges I?zditce
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4.4 Geometric Chmges Iiid~lrcecl bj
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4 5 Mer1iodolog.v of Raiii~11 Studi
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4.7 Poly(p-pheiq.lene) 217 with an
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4.7 Pol)~(p-pheiz~~lene) 219 ENERGY
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is worthwhile pointing out that the
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~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 801 Table 4-3
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4.7 Poly(y-phenylene) 225 Figure 4-
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Table 4-4. Observed Raman frequenci
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4.8 Other Polwieys 229 Table 4-5. T
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under various models. According to
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4. I0 Mechnriism oj Charge. Transpo
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4.12 Reftrences 235 [ 131 Kuzmany,
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4.12 References 237 [98j Matsunuma,
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5 Vibrational Spectroscopy of Polyp
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5.2 FOYCC Fields 241 such calculati
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5.2 Force Fields 243 accounts for o
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5.2 Force Fields 245 centers of the
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5.2 Force Fields 247 ture with conf
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5.3 Amide Modes 249 to the nh initi
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5.3 Ainide Modes 251 Table 5-1. Ami
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Table 5-2. Some amide modes of four
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5.3 Amidc Modes 255 Figure 5-1. Opt
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5.4 Polypeptides 257 nonhydrogen-bo
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5.4 Polvpeptida 259 Figure 5-2. Ant
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I 5.4 Polypeptides 261 )I .- + $ 80
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1226M 1222s (1 1165W 1167s (1 1120V
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135s 9 1 Ms1i 122Wbr 147 NH ob(37)
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5.4 Polypeptides 267 glycine residu
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5.4 Polypeptides 269 Raman bands in
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5.4 Polypeptides 271 Figure 5-7. St
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Frequency (cm-'1 100% b 700 500 300
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5.4 Polypptidt~s 215 Table 5-9. Obs
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~~ ~~ ~~~ ~ ~ ~~ 5.4 Polypeptides 2
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5.4 Poliyeptides 219 Table 5-11. Co
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Table 5-12. Aniide mode frequencies
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1351 Lifson, S., Stern, P. S., J. C
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5.6 Refeverices 285 [130] Tiffany,
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Index Amide modes 249 Amorphous pol
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Step-scan FTIR spectroscopy 14,34 -
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