Copper reflectance spectra

Figure 4. Reflection spectrum of an oxidized copper film exposed to 0.010M acetic acid in ethanol. The dashed line is the spectrum after a 4-h exposure of a fresh substrate to the acetic acid solution. Also shown are the IR peak positions from the gas-phase exposure spectrum (1).

Zhdanov and Vorona have made a detailed X-ray study of the effects of temperature upon the various forms of copper phthalocyanine (381). If copper phthalocyanine is sublimed between 150° and 250°C, the a modification is observed. Below this temperature range, the a modification is mixed with another unknown form. Heating for 20 minutes at 315°C or evaporation at 280°-300°C produces the 8 modification. The a and 8 forms of copper phthalocyanine differ in tinctorial power. The reflectance spectrum of the a form exhibits a fairly broad band at 480-487 m/i while this band occurs at 475-478 mu in the 8 form (317). An X-ray diffraction curve has been reported (80) for a third, y, form of copper phthalocyanine (212). The interplanar spacings for this complex are compared in Table III with... 

It will be seen from Eq. (4.5) that the angular dispersion is inversely related to the 2d spacing of the analyzing crystal. This is illustrated in Fig. 4.4, which shows the copper K spectrum recorded with a LiF(200) crystal, 2d = 4.028 A and a KAP crystal, 2d = 26.4 A. As would be predicted from Eq. (4.5), the angular separation of the Ka and K S lines is more than six times greater with the LiF(200) spectrum. Note also the greater reflecting power of LiF(200), which for Cu Ka is almost 30 times better than KAP. 

Figure 7.40. Simulated spectra of isotropic 10-A film of cuprous ethyl xanthate complex (a) (1) transmission spectrum (2) reflection spectrum of film deposited on copper measured with p-polarization, at angles of incidence of 80° (solid line) and 20° (x50, dashed line). Reprinted, by permission, from J. A. Mieiczarski, J. Phys. Chem. 97, 2649 (1993), p. 2651, Fig. 3. Copyright 1993 American Chemical Society (b) Reflection p- (solid line) and s-polarized (dashed lines) spectra of film on CU2S probed through ZnSe window at angles of incidence of 45° and water interlayer 1 n-m thick. Adapted, by permission, from J. A. Mieiczarski, E. Mieiczarski, J. Zachwieja, and J. M. Cases, Langmuir 11, 2787 (1995), p. 2792, Fig. 3. Copyright 1995 American Chemical Society.

The diffuse reflectance spectrum of d copper dimethoxide showed broad asymmetric bands with a maximum in the range 13 800-16 000 cm and these bands were assumed... 

Whereas ATR spectroscopy is most commonly applied in obtaining infrared absorption spectra of opaque materials, reflection-absorption infrared spectroscopy (RAIRS) is usually used to obtain the absorption spectrum of a thin layer of material adsorbed on an opaque metal surface. An example would be carbon monoxide adsorbed on copper. The metal surface may be either in the form of a film or, of greaf imporfance in fhe sfudy of cafalysfs, one of fhe parficular crysfal faces of fhe mefal. 

The simple free electron model (the Drude model) developed in Section 4.4 for metals successfully explains some general properties, such as the filter action for UV radiation and their high reflectivity in the visible. However, in spite of the fact that metals are generally good mirrors, we perceive visually that gold has a yellowish color and copper has a reddish aspect, while silver does not present any particular color that is it has a similarly high reflectivity across the whole visible spectrum. In order to account for some of these spectral differences, we have to discuss the nature of interband transitions in metals. 

The IR and Raman spectra of benzotriazole, benzotriazole anion and its Cu(I) complex have been measured. The characteristic peaks in the IR spectrum of the triazole moiety in benzotriazole anion occur at 1163 cm , 1134 cm , and 1115 cm . A broad band with a main peak at 1151 cm occurs in the spectrum of the Cu(I)-BTA complex <85JST(l00)57i>. The chemisorption of benzotriazole on clean copper and cuprous oxide surfaces is investigated by combining XPS, UV-PE and IR reflection absorption spectroscopy (IRAS). Coordination geometry including the triazole-... 

Figure 11 shows the PAXAS spectrum and the absorption spectrum of the copper sample. Quite corresponding fine structure shows that the information of EXAFS is also included in the PAXAS spectrum. The heat generation process also reflects the EXAFS. The only difference is the monotonous increasing trend of PAXAS signal intensity along with the photon energy increase. This is also seen in the previous... 

The [Cr(en)3]2+ and [Cr(pn)3]2+ salts have reflectance spectra (Table 11) resembling those of the hexaammines, and the six N donor atoms are assumed to complete tetragonally distorted octahedra around the metal. Stability constant measurements (Table 39) have shown that the ions [Cr(en)(aq)]2+ (vmax= 18 300 cm-1, e = 25 dm3 mol-1 cm-1) and [Cr(en)2(aq)]2+ (vma = 17 500 cm-1, e = 17 dm3 mol-1 cm-1) exist in aqueous solution, but that, as in the copper(II) system, the third ethylenediamine molecule is only weakly bound, and care is needed to prevent loss of en from tris(amine) complexes in the preparations. Several bis(amine) complexes, e.g. [CrBr2(en)2], have been isolated, and these are assigned trans structures because of IR spectral resemblances to the corresponding oopper(II) complexes. Since the spectrum of [Cr(S04)(en)2] also shows the presence of bidentate sulfate, this is assigned a trans octahedral structure with bridging anions. 

In the extreme class III behaviour,360-362 two types of structures were envisaged clusters and infinite lattices (Table 17). The latter, class IIIB behaviour, has been known for a number of years in the nonstoichiometric sulfides of copper (see ref. 10, p. 1142), and particularly in the double layer structure of K[Cu4S3],382 which exhibits the electrical conductivity and the reflectivity typical of a metal. The former, class IIIA behaviour, was looked for in the polynuclear clusters of copper(I) Cu gX, species, especially where X = sulfur, but no mixed valence copper(I)/(II) clusters with class IIIA behaviour have been identified to date. Mixed valence copper(I)/(II) complexes of class II behaviour (Table 17) have properties intermediate between those of class I and class III. The local copper(I)/(II) stereochemistry is well defined and the same for all Cu atoms present, and the single odd electron is associated with both Cu atoms, i.e. delocalized between them, but will have a normal spin-only magnetic moment. The complexes will be semiconductors and the d-d spectra of the odd electron will involve a near normal copper(II)-type spectrum (see Section 53.4.4.5), but in addition a unique band may be observed associated with an intervalence CuVCu11 charge transfer band (IVTC) (Table 19). While these requirements are fairly clear,360,362 their realization for specific systems is not so clearly established. 

As an example, both monofunctional and multifunctional polymeric mercapto-esters were deposited onto optically smooth silicon wafers coated with vapor-deposited copper. The copper had been oxidized to Cu20, as verified by XPS. Infrared reflectance (RAIRS) at 81° (4 cm-1 resolution, 2000 scans) using an MCT detector yielded information on both the nature and the durability of the mercaptoester bond to the metal oxide film. A 16 cm l shift (1740— 1724 cm-1) was observed in the carbonyl absorption of stearyl thioglycolate (STG) deposited onto the Cu20 mirror. The absorption spectrum of the carbonyl region is illustrated in Fig. 11, both for the pure STG and the reacted monolayer. 

---