Half Bandwidth Research Articles

Visual pigment composition in zebrafish: Evidence for a rhodopsin–porphyropsin interchange system

Numerous reports have concluded that zebrafish (Danio rerio) possesses A1-based visual pigments in their rod and cone photoreceptors. In the present study, we investigated the possibility that zebrafish have a paired visual pigment system. We measured the spectral absorption characteristics of photoreceptors from zebrafish maintained in different temperature regimes and those treated with exogenous thyroid hormone using CCD-based microspectrophotometry. Rods from fish housed at 15 degrees C and 28 degrees C were not significantly different, having lambda max values of 503 +/- 5 nm (n = 106) and 504 +/- 6 nm (n = 88), respectively. Thyroid hormone treatment (held at 28 degrees C), however, significantly shifted the lambda max of rods from 503 +/- 5 nm (n = 194) to 527 +/- 8 nm (n = 212). Cone photoreceptors in fish housed at 28 degrees C (without thyroid hormone treatment) had lambda max values of 361 +/- 3 nm (n = 2) for ultraviolet-, 411 +/- 5 nm (n = 18) for short-, 482 +/- 6 nm (n = 9) for medium-, and 565 +/- 10 nm (n = 14) for long-wavelength sensitive cones. Thyroid hormone treatment of fish held at 28 degrees C significantly shifted the lambda max of long-wavelength sensitive cones to 613 +/- 11 nm (n = 20), substantially beyond that of the lambda max of the longest possible A1-based visual pigment (approximately 580 nm). Thyroid hormone treatment produced smaller shifts of lambda max in other cone types and increased the half-band width. All shifts in photoreceptor lambda max values resulting from thyroid hormone treatment matched predictions for an A1- to A2-based visual pigment system. We therefore conclude that zebrafish possess a rhodopsin-porphyropsin interchange system that functions to spectrally tune rod and cone photoreceptors. We believe that these observations should be carefully considered during analysis of zebrafish spectral sensitivity.

Gold and colloidal gold surface influence on dna conformational change

DNA conformational changes caused by gold and colloidal gold surface have been studied by surface enhanced infrared spectroscopy (SEIRA), spectroscopy of plasmon reso- nance (SPR), atomic force microscopy (AFM) and principal component analysis. Experimen- tal data have shown that DNA conformation is slightly influenced by gold surface, while it is strongly altered by colloidal gold. Spectroscopic features of DNA-colloidal gold system have shown that the intensity of the asymmetric PO2 n band at 1240 cm n1 decreases by two times, and that of symmetric band at 1090 cm n1 decreases by 2.4 times whereas the halfwidth of phosphate bands increases by 35n40 cm n1 ; a frequency shift of asymmetric band position from 1240 to 1246 cm n1 and a symmetric band from 1090 to 1106 cm n1 has been observed. It was shown that intensity variation and shift of DNA base vibrations together with the broaden- ing of OH, NH, and CH stretching vibrations occur due to DNA conformational changes and the redistribution of the H-bonding network. A supposition about DNA condensation by colloidal gold was made. SEIRA and AFM data have showed major DNA structural changes occurred on gold colloidal particles. It was found that all the spectral features are more prominent for DNAncolloidal gold system deposited on gold substrate than on CaF2 substrate.

Infrared photoluminescence from TlGaS2 layered single crystals

AbstractPhotolimuniscence (PL) spectra of TlGaS2 layered crystals were studied in the wavelength region 500‐1400 nm and in the temperature range 15‐115 K. We observed three broad bands centered at 568 nm (A‐band), 718 nm (B‐band) and 1102 nm (C‐band) in the PL spectrum. The observed bands have half‐widths of 0.221, 0.258 and 0.067 eV for A‐, B‐, and C‐bands, respectively. The increase of the emission band half‐width, the blue shift of the emission band peak energy and the quenching of the PL with increasing temperature are explained using the configuration coordinate model. We have also studied the variations of emission band intensity versus excitation laser intensity in the range from 0.4 to 19.5 W cm‐2. The proposed energy‐level diagram allows us to interpret the recombination processes in TlGaS2 crystals. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Pressure-Induced Phase Transitions in trans-Stilbene Crystals

Abstract Pressure effects on the phase transitions in [1H12] and [2H12]trans-stilbene crystals were studied. Pressure–frequency plots and pressure–half band width plots for the Raman bands due to the inter- and intramolecular vibrations of [1H12] and [2H12]trans-stilbene crystals showed inflectional variations of the slopes of the plots at about 2 and 4 GPa. The fact that no clear discontinuous changes of the slopes of the plots were observed indicates that the second-order phase transitions take place at about 2 and 4 GPa. The low-frequency Raman bands of [1H12] and [2H12]trans-stilbene crystals were reinvestigated and assignments to the intermolecular rotational vibrations about the x, y, and z axes were made on the basis of the isotopic effect on the vibrational frequency.

OPTICAL CHARACTERISATION OF THERMALLY EVAPORATED NICKEL PHTHALOCYANINE THIN FILMS

Optical properties of thermally evaporated nickel phthalocyanine thin films have been characterised using spectrophotometric measurements of transmittance and reflectance in spectral range 200–2100 nm. The refractive index n and the absorption index k were calculated. Some of the optical absorption parameters, namely optical absorption coefficient (α), molar extinction coefficient (ε molar ), oscillator strength (f), electric dipole strength (q2) and absorption half bandwidth (Δλ) of the principal optical transitions have been also evaluated. The analysis of the spectral behaviour of the absorption coefficient (α), in the absorption region revealed indirect transitions. The fundamental and the onset energy gaps were estimated as 2.77±0.02 eV and 1.58±0.01 eV, respectively. According to the analysis of dispersion curves, the dielectric constants and dispersion parameters were obtained. The absorption measurements recorded in the UV–VIS region show two well defined absorption bands of phthalocyanine molecule, namely the Soret band (B) and the Q band. The Q band shows its characteristic splitting (Davydov splitting), and ΔQ was obtained as 0.21 eV. Discussion of the obtained results and their comparison with the previous published data are also given.

Characterization of Fine Metallic Soap Particles by X-Ray Diffraction, Differential Scanning Calorimetry, and Specific Surface Area Analysis

Fine metallic soap particles synthesized by jet mixing process have a much narrower particle size distribution and more homogeneous surface structure than metallic soap particles prepared by the method of pulverizing and classifying. With jet mixing, reaction conditions can be adjusted so as to control particle sizes while maintaining the above characteristics unchanged. With these particles it is possible to examine in detail the relationship between the particle size and condition and the crystalline condition and other physical properties, which has been considered impossible to perform using metallic soaps prepared by the conventional method of pulverizing and classifying. So, using fine particles of fatty acid zinc salt as a model of metallic soap for structure analysis, the influence of average particle size and fatty acid composition were examined on crystallinity, heat characteristics and other properties of the particles. Diffraction intensities, half-band widths, and long spacings of Miller index (003) peaks were analyzed from X-Ray Diffraction chart and compared with average particle size and fatty acid composition for fine particles of fatty acid zinc salt. Furthermore, Crystallinity of fine particles of fatty acid zinc salt were examined by these results, and were compared with results of differential scanning calorimetry and specific surface area analysis. The results are described in the present report.

Investigation of IR vibrational band of C–O bond of carbonyl species in Cu+-MFI zeolites

Interaction of CO molecules with Cu-MFI zeolites reduced in vacuum or CO atmosphere was investigated. The character of the absorption bands ascribed to intrazeolitic carbonyl species was explored in the dependence on the Cu loading, Si/Al ratio, degree of reduction and on the coverage of the Cu+ ions by CO molecules. The different character of individual Cu sites was revealed in the IR spectra of carbonyl species upon CO pressure. Some Cu ions are not able to form dicarbonyl species even at 7.5 kPa of CO. The band of residual monocarbonyl species strongly overlaps with the band of asymmetric vibration of dicarbonyl species, making the quantitative analysis of this band rather difficult. It was found that the position and the half-width of the monocarbonyl band, as well as the third and fourth statistical moment of the band are independent of the variable factors mentioned above. The main vibrational band of monocarbonyl species cannot be deconvoluted to individual bands corresponding to different Cu exchangeable sites. It means that IR spectroscopy of carbonyl species in the range of C–O stretching frequencies is not a suitable method for monitoring of the individual Cu+ sites in MFI zeolite framework. In addition, no correlation of –ΔHads and wavenumber of the fundamental vibration of C–O adsorbed on Cu+ ions in MFI zeolite matrix was found.

磁気共鳴画像法による対流運動の計測

This paper introduces a method for measurement of flow velocity using nuclear magnetic resonance (NMR) imaging. In a zinc electrodeposition bath, a convection of ZnSO4 solution was generated at a Rayleigh number of 2.7 × 1011. The electrolytic bath had a pair of horizontal zinc electrodes with a radius of 13 mm. Stejskal-Tanner plots of the fluid were measured with q gradients up to 41.5 mm-1. Probability density functions (average propagators) of the displacement of fluid in the q gradient interval Δ = 20 ms were obtained by Fourier transform of the Stejskal-Tanner plots. The half bandwidths of the average propagators with and without convection were 4.6 × 10-2 mm and 3.6 × 10-2 mm, respectively. Maps of the x, y, and z components of the flow velocity were calculated from phase maps. The half bandwidth of the average propagator obtained from the flow velocity map was 5.1 × 10-2 mm. These methods enable non-invasive and quantitative evaluation of transport phenomena by convection in electrodeposition processes.

A two band model for superconductivity: probing interband pair formation

We propose a two band model for superconductivity. It turns out that the simplest nontrivial case considers solely interband scattering, and both bands can be modeled as symmetric (around the Fermi level) and flat, thus each band is completely characterized by its half-band width $W_{n}$ (n=1,2). A useful dimensionless parameter is $\delta $, proportional to $W_{2}-W_{1}$. The case $\delta =0$ retrieves the conventional BCS model. We probe the specific heat, the ratio gap over critical temperature, the thermodynamic critical field and tunneling conductance as functions of $\delta $ and temperature (from zero to $T_{c}$). We compare our results with experimental results for $MgB_{2}$ and good quantitative agreement is obtained, indicating the relevance of interband coupling. Work in progress also considers the inclusion of band hybridization and general interband as well as intra-band scattering mechanisms.

Efficient red organic light-emitting devices based on a europium complex

An efficient organic light-emitting device using a trivalent europium (Eu) complex Eu(Tmphen)(TTA)3 (TTA=thenoyltrifluoroacetone, Tmphen=3,4,7,8-tetramethyl-1,10-phenanthroline) as the dopant emitter was fabricated. The devices were a multilayer structure of indium tin oxide/N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl-4,4-diamine (40 nm)/ Eu complex:4,4-N,N-dicarbazole-biphenyl (1%, 30 nm)/2,9-dimethyl,4,7-diphenyl-1,10phenanthroline (20 nm)/AlQ (30 nm)/LiF (1 nm)/Al (100 nm). A pure red light with a peak of 612 nm and a half bandwidth of 3 nm, which is the characteristic emission of trivalent europium ion, was observed. The devices show the maximum luminance up to 800 cd/m2, an external quantum efficiency of 4.3%, current efficiency of 4.7 cd/A, and power efficiency of 1.6 lm/W. At the brightness of 100 cd/m2, the quantum efficiency reaches 2.2% (2.3 cd/A).

Thermodynamic properties of the hydrogen bonded complexes between N-substituted anilines and proton acceptors

The influence of temperature, within the range 285–340 K, on spectral characteristics of ν(NH) absorption bands in ‘free’ N -methyl aniline, N -ethyl aniline, diphenylamine and N -methyl-4-nitroaniline in CCl 4 as well as in their hydrogen bonded complexes with acetonitrile, tetrahydrofurane, dimethylformamide (DMF), dimethylsulfoxide (DMSO) and hexamethylphosphoramide (HMPA) was studied. Spectral moments of ν(NH) absorption bands were determined: M (0) —the zero spectral moment (integrated intensity), M (1) —the first spectral moment (the centre of band gravity), M (2) —the second central moment as well as ‘effective’ half width of absorption band (Δν 1/2 ) eff =2( M (2) ) 1/2 . The coefficients of the linear correlation of these parameters with a temperature variation Y = aT + b ( Y = M (0) , M (1) , 2( M (2) ) 1/2 ) were calculated for ‘free’ and hydrogen-bonded molecules. It was demonstrated that these spectral characteristics considerably depend on the character of the N-substitute. The difference in the position of absorption bands ν m (NH) in the spectra for non-bonded molecules of N-substituted anilines in CCl 4 is caused by σ–π conjugation of alkyl radicals with the N atom and substitute polarization influence. Thermodynamic parameters −Δ H and Δ S of the complex formation process between amines and proton acceptors were determined from the temperature dependence of the equilibrium constants on the basis of van't Hoff equation. The increase of −Δ H enthalpy was observed in the rows of proton donors: N -alkyl-substituted anilines, diphenylamine and N -methyl-4-nitroaniline; and proton acceptors: acetonitrile, tetrahydrofurane, DMF, DMSO and HMPA. The correlations between −Δ H values and the shift of the first spectral moment Δ M c (1) = M m (1) − M c (1) , on the one hand, and −Δ H values and the increment of the square root of integrated intensity Δ B 1/2 = B c 1/2 − B m 1/2 , on the other hand, were found on passing from free to bonded molecules. However, the proportionality factor α in the equation −Δ H =αΔ B 1/2 depends on individual characteristics of proton donors and remains the same for each proton donor in the row of proton acceptors.

Thermodynamic properties of the hydrogen bonded complexes between N-substituted anilines and proton acceptors

The influence of temperature, within the range 285–340 K, on spectral characteristics of ν(NH) absorption bands in ‘free’ N-methyl aniline, N-ethyl aniline, diphenylamine and N-methyl-4-nitroaniline in CCl 4 as well as in their hydrogen bonded complexes with acetonitrile, tetrahydrofurane, dimethylformamide (DMF), dimethylsulfoxide (DMSO) and hexamethylphosphoramide (HMPA) was studied. Spectral moments of ν(NH) absorption bands were determined: M (0)—the zero spectral moment (integrated intensity), M (1)—the first spectral moment (the centre of band gravity), M (2)—the second central moment as well as ‘effective’ half width of absorption band (Δν 1/2) eff=2( M (2)) 1/2. The coefficients of the linear correlation of these parameters with a temperature variation Y= aT+ b ( Y= M (0), M (1), 2( M (2)) 1/2) were calculated for ‘free’ and hydrogen-bonded molecules. It was demonstrated that these spectral characteristics considerably depend on the character of the N-substitute. The difference in the position of absorption bands ν m(NH) in the spectra for non-bonded molecules of N-substituted anilines in CCl 4 is caused by σ–π conjugation of alkyl radicals with the N atom and substitute polarization influence. Thermodynamic parameters −Δ H and Δ S of the complex formation process between amines and proton acceptors were determined from the temperature dependence of the equilibrium constants on the basis of van't Hoff equation. The increase of −Δ H enthalpy was observed in the rows of proton donors: N-alkyl-substituted anilines, diphenylamine and N-methyl-4-nitroaniline; and proton acceptors: acetonitrile, tetrahydrofurane, DMF, DMSO and HMPA. The correlations between −Δ H values and the shift of the first spectral moment Δ M c (1)= M m (1)− M c (1), on the one hand, and −Δ H values and the increment of the square root of integrated intensity Δ B 1/2= B c 1/2− B m 1/2, on the other hand, were found on passing from free to bonded molecules. However, the proportionality factor α in the equation −Δ H=αΔ B 1/2 depends on individual characteristics of proton donors and remains the same for each proton donor in the row of proton acceptors.

Intermediate region between large and small polarons in many-electron systems

An analytical approach has been developed for a many-electron Holstein model in one, two, and three dimensions. We show that our approach is flexible and physically clear because it is based on perturbation theory. When the dimensionless ratio ${\ensuremath{\omega}}_{p}/2\mathrm{Dt}$ $(2\mathrm{Dt}$ is the half bandwidth in D dimensions) is small, ${\ensuremath{\omega}}_{p}/2\mathrm{Dt}\ensuremath{\ll}1,$ our result is similar to that of the Migdal-Eliashberg theory. When ${\ensuremath{\omega}}_{p}/2\mathrm{Dt}g1,$ our result approaches that of the Lang-Firsov transformation and small polaron theory. We have calculated the Green's function, the effective mass of electrons at the Fermi surface, the number of electrons ${n}_{\mathbf{k}}$ in a momentum state $\mathbf{k},$ and the jump of ${n}_{\mathbf{k}}$ at the Fermi surface to show that the perturbation approach works well in the intermediate region in which ${\ensuremath{\omega}}_{p}/2\mathrm{Dt}\ensuremath{\sim}1.$

Structural and optical studies of thermally evaporated CoPc thin films

The structure of the thermally evaporated cobalt phthalocyanine (CoPc) thin film in the β-form is investigated, and shows a single strong peak indicating preferential orientation in the (1 0 0) direction. Some structural parameters such as crystallite grain size, dislocation density and the number of crystallites per unit surface area are determined. The spectral parameters are determined by applying the electronic orbital transitions. But the optical parameters are deduced using band-model consideration for thin films of Pc. The spectral and optical parameters have also been investigated by using the spectrophotometric measurements of transmittance and reflectance in the wavelength range 200– 2500 nm . The absorption spectra recorded in the UV–VIS region show two absorption bands of phthalocyanine (Pc) molecule, namely the Soret band (B) and the Q-band. The Q-band shows its characteristic splitting (Davydov splitting) with ΔQ=0.23 eV . Some of the important spectral parameters, namely optical absorption coefficient ( α), molar extinction coefficient ( ε molar), oscillator strength ( f), electric dipole strength ( q 2) and absorption half bandwidth (Δ λ) of the principle optical transitions have been evaluated. The fundamental and the onset indirect energy gaps could be estimated as 2.90 + or − 0.05 and 1.51 eV , respectively. The refractive index showed an anomalous dispersion in the absorption region as well as normal dispersion in the transparent region. From analysis of dispersion curves, the dielectric constants, the dispersion parameters and the molar polarizability were obtained. All the above parameters were obtained for films as deposited and as annealed. No remarkable annealing effect on many parameters was observed.

Infrared difference spectroscopy: Part I. Interpretation of the difference spectrum

This paper presents a novel interpretation of difference spectra. The frequencies of the extremes in a difference spectrum do not correspond to the actual band maximum frequencies in the original spectra when the frequency difference of the two bands is less than 150% of the band halfwidth (Hw). In order to alleviate frequency distortions, an application of even derivatives (second and fourth derivatives) of the difference spectrum is proposed. The intensity of the corresponding bands before subtraction can be calculated from the known band frequency and the halfwidth estimated from the difference spectrum. The original calculated intensity may serve as an indicator of the band structure. The calculated band parameters (intensity, frequency, and halfwidth) may further serve as reliable initial values for the band fitting algorithm applied to the original and/or difference spectrum.

An ab initio model of electron transport in hematite (α-Fe2O3) basal planes

Transport of conduction electrons through basal planes of the hematite lattice was modeled as a valence alternation of iron cations using ab initio molecular orbital calculations and electron transfer theory. A cluster approach was successfully implemented to compute electron-transfer rate-controlling quantities such as the reorganization energy and electronic coupling matrix element. Localization of a conduction electron at an iron lattice site is accompanied by large iron–oxygen bond length increases that give rise to a large internal component of the reorganization energy (1.03 eV). The internal reorganization energy calculated directly is shown to differ from Nelsen’s four-point method due to the short-range covalent bridge interaction between the Fe–Fe electron transfer pair in the hematite structure. The external reorganization energy arising from modification of the lattice polarization surrounding the localization site is predicted to contribute significantly to the total reorganization energy. The interaction between the reactants and products electronic states near the crossing-point configuration is 0.20 eV and is consistent with an adiabatic electron-transfer mechanism. Electron transfer is predicted to possess a small positive activation energy (0.11 eV) that is in excellent agreement with values deduced from conductivity measurements. Measured electron mobility can be explained in terms of nearest-neighbor electron hops without significant contribution from iron atoms further away. Comparison of the predicted maximum polaron binding energy with the predicted half bandwidth indicates compliance with the small-polaron condition. Therefore the localized electron treatment is appropriate to describe electron transport in this system.

Dipole Strengths of the Qy(0,0) Bacteriochlorophyll c Transition¶

The absorption spectra of bacteriochlorophyll (BChl) c solutions in two mixtures of two solvents (acetonitrile with pyridine and dimethylsulfoxide with methanol) exhibiting different refractive indices were measured and deconvoluted into Gaussian components. The refractive index of mixed solvents was changed by the change in the ratio of the volumes of the liquids used in the mixture. Using the Qy(0,0) band half widths and absorption coefficient, based on the simplified formula proposed by Knox, the dipole strengths of the Qy(0,0) BChl c transition for various values of solvent refractive index were calculated and compared with values given by Knox and Spring. For both investigated combinations of two liquids, the dependence of Qy(0,0) transition dipole strength of the BChl c on solvent refractive index was almost linear. The slopes of the lines obtained from the experimental absorption bands were different for two investigated solvent mixtures. More accurate linear dependence and similar slopes of lines for both solvent mixtures were obtained using half widths and absorption coefficients of the Gaussian components of Qy(0,0) transition. It is explained by the superposition of the contributions from other electronic and vibronic transitions of BChl c monomers or possibly also from transitions of the pigments involved in some complexes with solvent molecules in the absorption region investigated. The results show that the formula proposed by Knox can be successfully applied also for BChl c, after elimination of the overlapped contributions from the other transitions, by applying Gaussian analysis to select only contribution from Qy(0,0) pigment transition.

Correlation between the Optical Properties and Structure of GRS-Active Substrates Based on Silver Films

The relationship between the optical properties of GRS-active substrates based on silver films and the parameters of their surface roughness have been studied by methods of mathematical statistics (correlation, regression, and factor analyses). The equations of nonlinear regression connecting these quantities were obtained. It is established that most correlatable are the maximum value of the optical density with the distance between islands and with the coefficient of their shape, and also its relation to the halfwidth of the optical density band of a silver film with the mentioned characteristics of the islands.

Synthesis and properties of substituted (p-aminostyryl)-1-(3-sulfooxypropyl)pyridinium inner salts as a new class of two-photon pumped lasing dyesElectronic supplementary information (ESI) available: synthesis details for compounds 7b, 7c, 8b and 8c. See http://www.rsc.org/suppdata/jm/b3/b307504d/

A series of substituted (p-aminostyryl)-1-(3-sulfooxypropyl)pyridinium (ASSP) inner salts have been synthesized and characterized. For comparison purposes substituted (p-aminostyryl)pyridinium iodide (ASPI) salts and substituted (p-aminostyryl)pyridinium tosylate (ASPT) salts were also prepared. Their linear absorption, two-photon absorption and emission properties have been studied. All these dyes exhibit relatively large two-photon absorption (TPA) cross-section values at a wavelength of 1064 nm. When pumped by a 1064 nm IR laser beam, two-photon pumped (TPP) frequency up-conversion lasing was observed in all these dyes, except for trans-4-{p-[N-methyl-N-(2-acetic acid ethyl ester)amino]styryl}-1-methylpyridinium tosylate (8b). The TPP lasing peaks of these dyes range from 612 nm to 637 nm, with half bandwidths varying from 2 nm to 11 nm. Compared with the substituted ASPI salts or the substituted ASPT salts, the substituted ASSP inner salts show enhanced TPP lasing. The TPP lasing efficiency of the trans-4-{p-[N-ethyl-N-(2-hydroxyethyl)amino]styryl}-1-(3-sulfooxypropyl)pyridinium inner salt (6e) is as high as 27%.

Magnetic compass orientation in European robins is dependent on both wavelength and intensity of light.

Magnetic compass orientation in birds has been shown to be light dependent. Results from behavioural studies indicate that magnetoreception capabilities are disrupted under light of peak wavelengths longer than 565 nm, and shifts in orientation have been observed at higher light intensities (43-44x10(15) quanta s(-1) m(-2)). To investigate further the function of the avian magnetic compass with respect to wavelength and intensity of light, we carried out orientation cage experiments with juvenile European robins, caught during their first autumn migration, exposed to light of 560.5 nm (green), 567.5 nm (green-yellow) and 617 nm (red) wavelengths at three different intensities (1 mW m(-2), 5 mW m(-2) and 10 mW m(-2)). We used monochromatic light of a narrow wavelength range (half bandwidth of 9-11 nm, compared with half bandwidths ranging between 30 nm and 70 nm used in other studies) and were thereby able to examine the magnetoreception mechanism in the expected transition zone between oriented and disoriented behaviour around 565 nm in more detail. We show (1) that European robins show seasonally appropriate migratory directions under 560.5 nm light, (2) that they are completely disoriented under 567.5 nm light under a broad range of intensities, (3) that they are able to orient under 617 nm light of lower intensities, although into a direction shifted relative to the expected migratory one, and (4) that magnetoreception is intensity dependent, leading to disorientation under higher intensities. Our results support the hypothesis that birds possess a light-dependent magnetoreception system based on magnetically sensitive, antagonistically interacting spectral mechanisms, with at least one high-sensitive short-wavelength mechanism and one low-sensitive long-wavelength mechanism.