The possibility of using porous silicon layers as antireflection coating instead of the antireflection coatings in common silicon solar cells was investigated. A technology for the manufacture of porous silicon antireflection layers on the emitter of n⁺ - p junctions with the already deposited contacts grid was developed. The careful investigation of the photovoltaic and optical characteristics of solar cells with porous silicon antireflection coating compared with the performances of solar cells using a well known ZnS antireflection coating is presented. It is shown that the formation of the porous layer under optimum technological regimes leads to decrease of reflection and improvement of the main photovoltaic parameters - short-circuit current and open-circuit voltage. A means of determining the porous silicon layer thickness through capacitance measurements is suggested.

Simple quantitative performance criteria are developed for translucent materials in terms of hemispherical visible transmittance, and angular spread of transmitted luminance using a half angle. Criteria are linked to applications in luminaires and skylights with emphasis on maximising visible throughput while minimising glare. These basic criteria are also extended to angle of incidence changes which are substantial. Example data is provided showing that acrylic pigmented with spherical polymer particles can have total hemispherical transmittance with weak thickness dependence, which is better than clear sheet, while the spread of transmitted light is quite thickness-sensitive and occurs over wider angles than inorganic pigments. This combination means significantly fewer lamps can achieve specified lux levels with low glare, and smaller skylights can provide higher, more uniform daylight illuminance.

The angular dependent optical properties of low-e and solar control glazings have been investigated in a European project, ADOPT, within the Standards Measurements and Testing programme. Two new predictive algorithms have been proposed and tested. One algorithm is based on an empirical formula and the other is based on a hybrid equivalent model, which approximates the actual coated glass. The validation procedure has included measurements as well as Fresnel calculations. The algorithms allow the user to calculate the solar heat gain coefficient versus angle of incidence for any transparent window combination without having to perform time-consuming measurements. For the tested window configurations the precision is mostly within one percentage point as compared to measured results.

The recent discovery that electromagnetic radiation can transmit super-efficiently through sub-wavelength holes in metal films and thin metal foils has implications for solar energy and energy efficiency technologies, especially thin metal films and metal particle arrays. The effect involves light induced surface plasmons coupling through the holes to form new states which can resonantly absorb and re-emit photons. They are a virtual bound state for photons. The material must have a dielectric constant below -1, and for noble metals enhancement is strong beyond (lambda) approximately 0.7 micrometers , with a long wavelength limit set by absorption losses, well into the black body spectral range. In aluminium the strong onset is in the visible. Thus control of solar heat gain and thermal radiation can utilize this effect. Broad band or narrow band spectral selectivity are possible, depending on metal thickness and how the holes are arranged with respect to each other. Very interesting effects occur in multilayers, with standard multilayer thin film optics not applying when this phenomena is present. An admittance approach to handling thin film optics in the presence of surface plasmon coupling is addressed.

The idea of the quantum dot solar cell, which provides a novel direction to the high-efficiency solar cell problem, is developed. A theoretical model is presented for a practical p-i-n quantum dot solar cell built on the base of the self-organized InAs/GaAs system. Study the advantages of the use of quantum dots in active region for photon absorption in the long-wavelength part of spectrum and increase in the efficiency of the conversion of solar energy in electrical power is carried out. Problems of theory and experiment of low-dimensional solar cells (quantum well and quantum dot solar cells) are discussed.

This paper deals with the large area deposition and coating properties of the thermo-stable (temperable/bendable) solar coating material, CuO, and some new optical coating systems comprising CuO films for architectural and automotive/transportation applications. The CuO solar coating is combined with other coating layers, for example, an anti-reflection film, a reflection film, a coloration coating layer, etc., which are also thermo-stable. The film systems are developed at the research laboratory by D.C. Magnetron reactive sputtering process. The new developed technologies then transferred to the production line. Product performances are compared before and after heat treatment of the coating systems. Performance tables and other physical properties, including optical parameters, mechanical and environmental stability, storage properties, etc., are also presented for this new product series.

A method was developed for the theoretical calculation of the reflectance for the antireflection coatings made of porous silicon. Although porous silicon has been the focus of interest for the past years, still a satisfactory concept for calculating the reflectance features is lacking. Towards this end, we suggest a new concept that is a combination of the optical matrix method and a graded-bandgap model of porous silicon, which takes into account the gradient in porosity. The calculations based on the optical matrix method were carried out for common antireflection coatings, as well, for MgF₂, ZnS and Ta₂O₅ in order to prove feasibility of the method. A rather good agreement with experimental data was found for all types of antireflection coatings. It is shown that the model of porous silicon as a graded-band semiconductor is valid and is a handy method for the reflectance calculation for porous silicon.

An effect of the increase in the efficiency of solar cells (in particular, common silicon solar cells) is described when these solar cells are immersed in an isotropic liquid dielectric. The presence of a dielectric thin film results in an increase in the efficiency of solar cells by 40-60% from the reference value. The current-voltage characteristic, fill factor and other main parameters of these solar cells are analyzed. The mechanisms responsible for the increase in the efficiency of solar cells are discussed.

Bifacial sunlit solar cells made of silicon p⁺nn⁺ structures are investigated theoretically. It is shown that the short circuit current, open circuit voltage, fill-factor and efficiency strongly depend on both p⁺n junction parameters and n⁺n isojunction. Possibilities of manufacturing high-efficiency bifacial solar cells using silicon p⁺nn⁺ structures are discussed.

Switchable windows can be used for a variety of applications including architectural and vehicle windows, aircraft transparencies, skylights and sunroofs. Related to glazing are applications for low-information content displays for the display of information. Switchable windows rely on a variety of processes and materials. Several companies throughout the world are developing dynamic glazing. University and National Laboratory groups are researching new materials and processes to improve these products. Switchable glazing for building and vehicle application is very attractive. Conventional glazing only offers fixed transmittance and control of energy passing through it. Given the wide range of illumination conditions and glare, a dynamic glazing with adjustable transmittance offers the best solution. This study covers selected switching technologies including, electrophoresis or suspended particles, electrochromism, liquid crystals, thermotropism and gaschromism. Currently much development in switchable devices is aimed at deposition processes suitable for glass substrates. In the future, there is movement towards plastic substrates for weight savings. Cost of production and defects in large-area deposition are two of the largest issues. These exciting technologies create many challenges and opportunities for glass and plastic companies along with excitement for building designers.

This paper deals superficially with three aspects of electrochromic smart windows. Their energy efficiency is discussed, and it is argued that a control strategy considering whether a room is in use or not can lead to large savings of the energy needed for space cooling. With regard to durability, it is shown that chemical compatibility between the electrolyte and the electrochromic films can be achieved without loss of optical transparency. Finally, we touch upon manufacturability and present data on precharging of electrochromic films by gas treatment and point at possibilities of using roll coating and continuous lamination of polyester foils.

The results of a 2000 survey of United States window manufacturers on the subject of switchable glass are discussed. The areas covered in this paper include awareness of the overall product category of switchable glass and various types of switchable glass, attitudes toward specific features of switchable glass, expectations for manufacturer production of such products, expectations for market penetration rates among end-product consumers, levels of price sensitivity among window manufacturers regarding switchable glass, and expectations for the pace of new product development within the window industry over the next five years.

Tantalum oxide (Ta₂O₅) thin films prepared by reactive magnetron sputtering are investigated for their potential use as the ionic conducting layer in all solid state monolithic electrochromic devices. The paper focuses on the influence of Ta₂O₅ coatings on the electrochromic response of amorphous tungsten oxide (a-WO₃), the methods employed for charging during monolithic device fabrication and associated charge losses caused by subsequent deposition of the component layers of monolithic (all solid state) electrochromic devices. The dependence of the electrochromic response and related charge loss processes have been studied for Ta₂O₅ films of different thicknesses prepared on a-WO₃ electrochromic films.

Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on Mg_zNiH_x samples with 0.8 less than z less than 3.7 shows that addition of one Mg atom per Mg₂Ni gives the best ab/desorption kinetics for hydrogen. X- ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure- composition isotherm of Mg₂NiH_x is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg₂NiH₄. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.

The dependence of the infrared spectral optical constants, n_(lambda ) and k_(lambda ), of electrochromic tungsten oxide thin films, prepared by reactive magnetron sputtering at different substrate temperatures, on the quantities of charge, q, inserted has been determined from spectrophotometric measurements of transmittance and reflectance. For WO₃ films deposited at temperatures greater than 200 degree(s)C significant infrared absorption is observed to rise with increasing levels of charge insertion. For the most crystalline films prepared at temperatures greater than 350 degree(s)C the rates of change dn_(lambda )/dq and dk_(lambda )/dq are greatest. The results provide essential design data for variable reflectance/emittance devices. Rear surface devices, which mask the reflectance of a highly reflective rear surface mirror through a charge dependent increase in k_(lambda ), have been successfully demonstrated using either liquid or solid electrolytes. Monolithic devices have been prepared using a hybrid combination of sputtered and electron-beam evaporated coatings.

Ionically self-assembled monolayers (ISAMs), fabricated by alternate adsorption of cationic and anionic components, yield exceptionally homogeneous thin films with sub- nanometer control of the thickness and relative special location of the component materials. Using organic electrochromic materials such as polyaniline, we report studies of electrochromic responses in ISAM films. Reversible changes in the absorption spectrum are observed with the application of voltages on the order of 1.0 V. Measurements are made using both liquid electrolytes and in all-solid state devices incorporating solid polyelectrolytes such as poly(2-acylamido 2-methyl propane sulfonic acid) (PAMPS). Due to the precise nanometer scale control of thickness and composition of the electrochromic composite system, switching times faster than 50 ms have been demonstrated.

In this study we investigate the structure, composition, diffusion coefficient, and electrochromic properties of nickel-vanadium oxide films as a function of deposition conditions. Polycrystalline films have been deposited by DC magnetron sputtering from a nonmagnetic target of Ni_0.93V_0.07 in an atmosphere of O₂/Ar and Ar/O₂/H₂, with the gas flow ratios varied systematically to cover the range from nearly-metallic to overoxidized films. The results contradict the usual view that films deposited in O₂/Ar are dark brown in their as-deposited state. While such films can easily be deposited, the optimum electrochromic properties have been observed at O₂/Ar ratios giving nearly transparent films. Addition of hydrogen to the sputtering atmosphere improved cycling stability of the films. The diffusion coefficient has been determined by the Galvanostatic Intermittent Titration Technique (GITT).

Molecular orbital (MO) calculations of nickel oxide clusters (Ni_xO_y) were conducted to elucidate their bonding and optical properties. Four model clusters, i.e., Ni₆O¹⁰⁺, NiO₆^10-, Ni₆O₁₉^26-, and Ni₁₄O₁₉^10-, were constructed and evaluated. As a reference, [Ni(H₂O)₆]²⁺ was also studied. It was revealed that HOMO of those clusters have O 2p and/or Ni 3d orbitals and expected optical transition is not so simple as the one expressed by Ni²⁺(3d⁸) implied by Ni²⁺(3d⁷ 4s¹) or Ni⁺(3d⁸ 4s¹). HOMO-LUMO gap of Ni₆O₁₉^26- was 4.66 eV very close to the experimental band gap Eg equals 3.1 to approximately 4.3 eV for NiO crystal and not affected by the embedding into Madelung potential, which indicates that this cluster can be a minimal structure representing the optical properties of crystal NiO.

Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl₆) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO₃ structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO₃/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm²/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

The electrochromic properties of sol-gel and mesoporous tungsten oxide thin films were investigated. Tungsten oxide films were prepared by a spin coating technique from an ethanolic solution of tungsten hexachloride. A block copolymer (BASF Pluronic p₁₂₃, (p₁) was employed as a template to generate the mesoporous structure. The electrochromic and optical properties of such films are described and compared to standard sol-gel tungsten oxide films. A novel ultraviolet (UV) illumination method was developed to remove the polymer templates and was found to improve the coloration efficiency of tungsten oxide in general. All types of films were analyzed by transmission electron microscopy (TEM), atomic force microscopy (AFM), x- ray diffractometry and cyclic voltammetry.

Sputtered thin films of amorphous tungsten oxide were deposited onto glass substrates coated by conductive indium- tin oxide. The films were sputtered in Ar/O₂ with different oxygen contents. Elastic Recoil Detection Analysis determined the density and the stoichiometry while x-ray diffraction gave evidence of the amorphous character. The films were electrochemically intercalated with lithium ions. At several intercalation levels the optical reflectance and transmittance was measured in the wavelength range 0.3 micrometers to 2.5 micrometers . We study the effect of different sputtering conditions on the coloration efficiency of the films. Films deposited at pressures of 80 mTorr showed a distinctly different absorption spectrum after intercalation, as compared to films sputtered at lower pressure. Sputtered substoichiometric tungsten oxide exhibits an absorption peak similar to the case of lithium intercalation. Substoichiometric films can be made transparent by deintercalation.

Intercalation of lithium ions in amorphous tungsten oxide films and in monoclinic polycrystalline tungsten oxide films has been studied using electrochemical analyses and Raman spectroscopy. We present direct evidence for W⁵⁺ 5d- electron localization in amorphous tungsten oxide films upon lithium ion and electron intercalation, by comparing the Raman spectra of amorphous and crystalline tungsten oxide films. We observe that when lithium ions and electrons are inserted into the crystalline tungsten oxide films, the monoclinic structure of the material proceeds to progressively increased symmetry. On the other hand, when lithium ions and electrons are inserted into amorphous tungsten oxide films, the inserted electrons are localized in W⁵⁺ sites and polarize their surrounding lattice to form small polarons. The extra Raman peaks due to the W⁵⁺-O single bonds and W⁵⁺equalsO double bonds appear at 330 and 450 cm^-1, respectively.

A detailed systematic study of the tungsten oxide thin films has been carried out using colored WO₃ films after they were annealed at progressively increasing temperatures ranging from 350 to 450 degree(s)C in oxygen environments. The structural properties of the films were characterized using x-ray diffraction (XRD) and Raman spectroscopy. The amorphous WO₃ films remain as an amorphous phase up to 385 degree(s)C and begin to crystallize at 390 degree(s)C and then are completely crystallized at 450 degree(s)C. Absorption peaks of the films are found to shift to a higher energy side with increasing annealing temperature up to 385 degree(s)C and then shift abruptly to a lower energy as the films begin to crystallize at 390 degree(s)C.

Lead titanate PbTiO₃(PT) thin films were prepared on single-crystal MgO(100) substrates by sol-gel process (SG) and pulsed laser deposition (PLD) techniques. The SG coating solutions were synthesized from lead (II) acetate, titanium isopropoxide precursors using acetic acid and diethanolamine (DEA). The SG films were spin coated at 2000 rpm, dried in air at 350 degree(s)C and rapid thermally annealed at between 400-650 degree(s)C temperature range. PLD films were grown at 2x10^-6 Torr chamber pressure in flowing oxygen and at the substrate temperature of 600 degree(s)C. The films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning spectrophotometry. The optical properties of the PT films were evaluated from spectral transmittance and reflectance measurements. Optical and structural properties of SG and PLD thin films grown at 600 degree(s)C substrate temperature were compared. XRD analysis indicates that PLD films grow strongly textured on MgO(100) substrate. In contrast, SG films were randomly oriented. SEM showed that the surface of the SG PT films heat treated at above 600 degree(s)C had smaller grains. In contrast PLD grown films had a well-developed dense and uniform grain structure with larger grain size. The optical constants such as refractive index (n), extinction coefficient (k) and optical band gap (E_g) values were found to depend on the preparation techniques. The optical band gap values are in the range of 2.98-3.24 eV depending on the deposition method.

An example high resolution three panel digital projection system utilizing Liquid Crystal On Silicon (LCOS) is discussed. Based on Three-Five's 1920x1200 Brillian LCOS panels the system yields full white/full black contrast of greater than 450:1, greater than 65% reflectivity at f/2.8. This paper will discuss LCOS properties and the considerations of implementation. Numerous advances have taken place in the reflective LCD domain over the past few years enabling tangible quality products. But more development is needed to further increase the quality and decrease the price. LCOS panels utilize semiconductor manufacturing methods and for example traditional twisted nematic fluids or hometropic materials. Reflective displays permit the drive electronics to be behind the pixels enabling the aperture ratios to be extremely high. The advantages are extremely high pixel counts at a relatively low cost. This technology enables products with a vast supply of resolution for the display of photo-realistic digital images.

We have used atomic force microscopy (AFM) tapping techniques to study the droplet cavity morphology of a Holographically-formed Polymer Dispersed Liquid Crystal (H- PDLC). The samples were created using a Coherent Verdi laser at 532 nm to holographically form a transmission grating structure within the liquid crystal / polymer composite. The gratings were removed from their glass substrates and the liquid crystal removed, allowing us to image the inside of the droplet cavities. We found that the surface structure is rough, and that the structure varies depending on the polymer used in the material set. One result is a cavity that has a dimpled morphology. We report our investigations of the material sets, which include AFM images, image analysis of the structures, and the potential implications of such structures on liquid crystal anchoring within the droplet cavities.

Polydiacetylene derivative of 2-methyl-4-nitroaniline (PDAMNA) shows a picosecond switching property, which illustrated a partial all-optical picosecond NAND logic gate. The switching phenomenon was demonstrated by waveguiding two collinear beams at 633 nm and 532 nm through a hollow fiber of 50 micrometers diameter, coated from inside with a thin film of PDAMNA. A Z-scan investigation of a PDAMNA thin film on quartz substrate revealed that the switching effect was attributed to an excited state absorption in the systems. The studies also showed that the polymer suffers a photo-oxidation beyond an intensity level of 2.9x10⁶ w/cm². The photo-oxidized film has different physical properties that are different from the original film before oxidation. The lifetime of both excited states before and after oxidation as well as their absorption coefficients were estimated by fitting a three level system model to the experimental results.

Vanadium dioxide (VO₂) is one of the most attractive thermochromic materials, which shows large changes in optical and electrical properties at transition temperature (Tt) close to room temperature. This thermochromic behavior has been explained by the Mott-Hubbard transition from a high-temperature rutile structure (metal phase) to a low-temperature monoclinic structure (semiconductor phase). Non-doped VO₂ are characterized by Tt of 68 degree(s)C, which is rather high for general window applications. However Tt have been reported to be decreased by W or Mo dopings in which W was the most effective dopant for reducing Tt. We already reported that rf magnetron sputtering using V₂O₃ or V₂O₅ targets enable us to deposit polycrystalline thermochromic VO₂ films with high reproducibility by introduction of oxygen gas (O₂/(Ar+O₂)equals1 to approximately 1.5%) or hydrogen gas (H₂/(Ar+H₂equals2.5 to approximately 10%), respectively, as reactive gases. In this study, ZnO polycrystalline films were deposited as a buffer layer between the VO₂ film and glass substrate also by rf magnetron sputtering (VO₂/ZnO/glass), where the ZnO films deposited on a glass substrate had been known to exhibit <001$GTR preferred orientation in the wide range of the deposition conditions.

In this paper, we design a novel 2x2 silicon-on-insulator (SOI) waveguide optical switch with X-crossing structure. With free- carrier plasma dispersion effect, we can construct such a device with X-crossing multimode interference region. Applying the X- crossing configuration, the input and output waveguides can be easily laterally separated for direct coupling to fiber without S-bending structure. We use a BPM simulation tool to simulate the output mode patterns and light propagations.

We applied a pumping field to couple the middle level of two- photon absorption with the fourth level. Two-photon absorption minimum was observed. This is the first observation and experimental analysis of such phenomenon after it was predicted four years ago. In sodium vapor, two-photon absorption strength of 3S_1/2(Fequals2)-3P_3/2-4D_3/2 was measured by detecting the fluorescence at 568.3 nm (4D_3/2-3P_1/2). Levels 3P_3/2 and 5S_1/2 were connected by pumping field. Experimental data of two-photon absorption strength vs detuning from middle level (TADM) shows that the two-photon absorption was reduced by 60% at line center in the presence of resonant pumping field. In rubidium vapor, two-photon absorption of 5S_1/2(Fequals3)-5P_3/2-8S_1/2(Fequals3) was measured by detecting the fluorescence at 607 nm (8S_1/2-5P_1/2). Levels 5P_3/2 and 5D_5/2(Fequals5) were connected by pumping field. The TADM profiles under different experimental condition indicate that the maximum reduction of two-photon absorption can be 80%. And the reduction effect reduced with lower strength, higher detuning frequency and wider line width of pumping field. At the same time, the position of minimum absorption depends on the detuning of pumping field. All the experimental profiles were fitted well with theoretical calculation results.

Thin films of WO₃ were deposited by DC magnetron sputtering at different oxygen partial pressures and different target surface oxidation states. Evaluation of the film properties was carried out using electrochemical and optical techniques. Electrochromic coloration efficiency is compared over a range of injected charge. Methods for determining the stoichiometry of the films are suggested. Excess electrochemically injected charge in the WO₃ films is quantified and related to super-stoichiometry. Absorption measured in the as-deposited films is quantified and related to sub-stoichiometry. Deposition rate is an important consideration in the development of cost models for production of electrochromic devices. For many types of dielectric thin films deposited in in-line sputtering systems, the only concern is the onset of optical absorption. For WO₃, many other aspects of the films' behavior may be affected. In this paper, ways to evaluate stoichiometry are examined in an effort to better understand the effect of changing process parameters on the films.

The long-established ferric ferrocyanide chromophore Prussian Blue (PB) has often been studied for electrochromic use. New observations and conclusions are now presented. Detailed analyses, chemical and by means of EDX, of films deposited on Pt in a variety of conditions and solution compositions, are presented, and a remarkably efficient uptake of Cs⁺ noted. In particular, the pH for stablest film from KCl- containing solution should be high, ca 4-5. Details of the electrodeposition on ITO glass were examined, where earlier suppositions regarding the nature of the foundation layers are confirmed by direct observation. Unexpectedly, this is substantially of ferric-ferricyanide composition. The spectroscopic shifts of the intervalence charge-transfer absorption on incorporation of different univalent cations into PB are reported and analysed. The preparative precautions needed for deposition on larger (10 x 10 cm²) ITO glass electrodes are thoroughly examined. The electrochromic response of a dual-PB electrode setup in which one electrode can be switched to clear Prussian White and the other to the deep yellow of Prussian Yellow, presents an unlikely prospect for windows or other intensity-attenuation applications, but may serve e.g. in displays. In an alternative dual-PB array a metallic silver electrode is peripherally interposed, to act as a silver/silver- chloride counter electrode. The response time in the 10 x 10 cm² system is approximately 90 s and is accompanied by a pronounced iris (racoon) effect. The assembly provides an interesting example of two-electrode operation of a larger (cf lab-scale) device. Two-electrode operation is discussed and clarified.

This report deals with comparison of the total hemispherical reflectances (THR), emissivities, and solar radiation absorption factors of coatings designed to reduce a stray light background and provide the thermal control both in space-based instruments and in land-based equipment. The THR measurement results are presented that have been carried out at 10 values of wavelengths within visible, near- ultraviolet, and near-infrared ranges (400 to 927 nm). The coatings being compared are as follows: chemically oxidized copper, coating on the basis of Al-N system, black-chromium coating, black bituminous paint, commercial black enamel used in solar converters, and plasmatron sputtered nichrome and constantan alloys. The chemically oxidized copper has been chosen as a material possessing high solar radiation absorption factor and low emissivity. Black-chromium coating is a widespread material for thermal control in space instruments. The black bituminous paint has been chosen as a possible cheap alternative solar absorber. Commercial black enamel served as a standard conventional coating used in some inexpensive solar converters. Nichrome and constantan have been also selected for investigations as the alloys having high specific resistivities, which promised that intensive electron scattering in skin layers of these alloys could take place, i.e., intensive transfer of energy and momentum received from the light wave to the lattice.