Reflexionsspektroskopie

Kortüm, G.

doi:10.1007/978-3-662-29788-9

Cited by 234 publications

(65 citation statements)

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“…42,48,49 Measurements of the pressure dependence of 10Dq pointed to a similar exponent 5 ≤ n ≤ 6. 50 For the sake of simplicity we have chosen e π,x = e π,y = 1/4e σ .…”

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confidence: 84%

Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO4

et al. 2011

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The bulk magnetic properties of the new quasi-one-dimensional Heisenberg antiferromagnet, CuCrO4, were characterized by magnetic susceptibility, heat capacity, optical spectroscopy, EPR and dielectric capacitance measurements and density functional evaluations of the intra-and inter-chain spin exchange interactions. We found type-II multiferroicity below the Néel temperature of 8.2(5) K, arising from competing antiferromagnetic nearest-neighbor (Jnn) and next-nearest-neighbor (Jnnn) intra-chain spin exchange interactions. Experimental and theoretical results indicate that the ratio Jnn/Jnnn is close to 2, putting CuCrO4 in the vicinity of the Majumdar-Ghosh point.

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“…42,48,49 Measurements of the pressure dependence of 10Dq pointed to a similar exponent 5 ≤ n ≤ 6. 50 For the sake of simplicity we have chosen e π,x = e π,y = 1/4e σ .…”

mentioning

confidence: 84%

Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO4

et al. 2011

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“…Spectral reflectance factors of Lambertian surfaces [13,14] are constrained to the range of zero to one. There is no obvious known constraint on the spectral variation; for instance, rare-earth glass powders have very highly articulated reflectance spectra [18]. However, even a cursory glance at databases of natural spectral reflectances reveals that generic articulations are structurally highly limited in their complexity.…”

Section: Theory Of Statistics Of Spectramentioning

confidence: 99%

“…The physics lets one move from the parameter values to the reflectance factors. It is indeed standard practice in reflection spectroscopy [18] to study the spectral signature k / s = ͑1−r 2 ͒ /2r rather than the-immediately observedreflectance r, because this non-linear function of r represents the absorption coefficient k divided by the scattering coefficient s.…”

Section: A Homomorphic Mappingsmentioning

confidence: 99%

The prior statistics of object colors

Koenderink¹

2010

J. Opt. Soc. Am. A

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The prior statistics of object colors is of much interest because extensive statistical investigations of reflectance spectra reveal highly non-uniform structure in color space common to several very different databases. This common structure is due to the visual system rather than to the statistics of environmental structure. Analysis involves an investigation of the proper sample space of spectral reflectance factors and of the statistical consequences of the projection of spectral reflectances on the color solid. Even in the case of reflectance statistics that are translationally invariant with respect to the wavelength dimension, the statistics of object colors is highly non-uniform. The qualitative nature of this non-uniformity is due to trichromacy.

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“…A model in which the scattering medium is approximated by plane-parallel layers has been used by numerous workers as a basis for reflectance theory [7,8]. We consider a pair of adjacent layers, with Ri R j and Ti,Tj as the reflectances and transmittanc~s for radiation incident in one direction, and RI RJ and TI, TJ as the reflectances and transmittan~es for radiation incident in the other direction.…”

Section: A the Layer Modelmentioning

confidence: 99%

The interpretation of diffuse reflectance spectra

Hecht¹

1976

J. RES. NATL. BUR. STAN. SECT. A.

185

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Numerous treatments of the diffuse r efl ecting properties of scattering media have been d escribed. Many theories give an adequate account of the refl ectance for a specific set of conditions for which the model was constructed and the soluti on t ested experimentally. Only those models which are considered to be fairl y general are considered her e.It is conveni ent to di vide the theories into those based upon continuum models and those based upon s tatistical models. The continuum m odels typica ll y describe the scatterin g a nd absorbin g properties of a given m edium in t erm s of two phenomenological constants. These models may all be regarded as varying levels of approxima t e soluti on to the general equation of radi ative tra nsfer. This provides a convenient basis for compariso n of the various theories.The statistical models a re based upon a summa tion of transmittances a nd r efl ectances fr om individual l ayers or parti cles. Thus, ~o m e ass um ptions must be m ade abo ut the n ature of the fund amenta l units, and the validity of the ultim a te result will depend upon how closely these assumptions correspond with r eality. Only the statistical models lead to ex pressions fr om which absolute absorptivities and sca ttering coefficients can be calculat ed and r elated to the actual particle characteristics.The relationship between the various models will be discussed and the features which typify the ab~o rptivity and scatterin g coeffici ent according to each will be compared and related to the available experimental data. This leads t o a consideration of the charac teristics of appropriate model systems and standards.Key words: Absolute absorptivities; continuum models; diffuse reflectance; r adiative transfer; reflectance spectra; scatt ering coefficients ; statistical models. List of Principal Symbols UsedH-integral of Chandrasekhar (equation (35) ) (Note: Where a given letter is used in both capital and lower case form (e.g., r,R and t,T), the capital letter refers to the macroscopic observable and the lower case letter to the corresponding variable for an individual particle or layer of the material. A bar over a given symbol means the average value for that variable). (5)) scattering function (equation (2)) source func tion (eq ua tion (4)) absorptivity Kubelka-Munk absorption constant (equations (16) and (17) H(iJ.)

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Reflexionsspektroskopie

Cited by 234 publications

References 0 publications

Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO4

Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO4

The prior statistics of object colors

The interpretation of diffuse reflectance spectra

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