We conducted an experiment to assess the predictive capability of a leaf optical meter for determining leaf pigment status of Acer mono Maxim., A. ginnala Maxim., Quercus mongolica Fisch., and Cornus alba displaying a range of visually different leaf colors during senescence. Concentrations of chlorophyll (Chl) a, Chl b, and total Chl [i.e., Chl (a+b)] decreased while the concentration of carotenoids (Car) remained relatively static for all species as leaf development continued from maturity to senescence. C. alba exhibited the lowest average concentration of Chl (a+b), Chl a, and Car, but the highest relative anthocyanin concentration, while Q. mongolica exhibited the highest Chl (a+b), Chl b, and the lowest relative anthocyanin concentration. A. mono exhibited the highest Chl a and Car concentrations. The relationships between leaf pigments and the values measured by the optical meter generally followed an exponential function. The strongest relationships between leaf pigments and optical measurements were for A. mono, A. ginnala, and Q. mongolica (R2 ranged from 0.64 to 0.95), and the weakest relationships were for C. alba (R2 ranged from 0.13 to 0.67). Moreover, optical measurements were more strongly related to Chl a than to Chl b or Chl (a+b). Optical measurements were not related to Car or relative anthocyanin concentrations. We predicted that weak relationships between leaf pigments and optical measurements would occur under very low Chl concentrations or under very high anthocyanin concentrations; however, these factors could not explain the weak relationship between Chl and optical measurements observed in C. alba. Overall, our results indicated that an optical meter can accurately estimate leaf pigment concentrations during leaf senescence - a time when pigment concentrations are dynamically changing - but that the accuracy of the estimate varies across species., Future research should investigate how species-specific leaf traits may influence the accuracy of pigment estimates derived from optical meters., G. Y. Li, D. P. Aubrey, H. Z. Sun., and Obsahuje bibliografii
This paper deals with an alternative method to determine the thickness of a thin film on a substrate. A linear relation between the thin-film thickness and the wavelength of the reflectance spectrum tangent to the envelope function for specific interference order is revealed in a wide wavelength range. This relation enables the calculation of the thickness provided that the wavelength-dependent optical parameters of the thin film and the substrate are known. The methods allow to calculate the thickness from the reflectance spectrum in a narrow range close to one extreme only as demonstrated both theoretically and experimentally for Sio2 thin-films on Si substrates. The results are discussed for two wavelength ranges and compared with those obtained by the algebraic fitting method. and Práce prezentuje metodu určení tloušťky tenké vrstvy z měření spektrální odrazivosti s využitím nové varianty obálkové metody. Byl nalezen lineární vztah mezi vlnovou délkou tečny spektrální odrazivosti k obálkové funkci a odpovídající tloušťkou tenké vrstvy pro daný interferenční řád v širokém spektrálním oboru. Tento lineární vztah umožňuje výpočet tloušťky vrstvy na základě známých spektrálních optických parametrů vrstvy a podložky. Metoda umožňuje výpočet tloušťky ze znalosti pouze malé části spektra v okolí jednoho extrému, jak je demonstrováno teoreticky a experimentálně na systému SiO2 - Si. Výsledky jsou porovnány s hodnotami, získanými algebraickou fitovací metodou.