Absorption broadband

The divalent rare-earth ion Eu has the 4f electronic configuration at the ground states and the 4f 5d electronic configuration at the excited states. The broadband absorption and luminescence of Eu are due to 4f - 4 f 5d transitions. The emission of Eu is very strongly dependent on the host lattice. It can vary from the ultraviolet to the red region of the electromagnetic spectrum. Furthermore, the 4f-5d transition of Eu decays relatively fast, less than a few microseconds [33]. 

The majority of currently deployed IR sensors operate in the near-IR. Although near-IR sensors suffer from limited selectivity and sensitivity due to the relatively unstructured broadband absorptions in this frequency range, the easy availability of waveguides and other instrumentation give this spectral range a significant advantage over the mid-IR. Main application areas involve substance identification and process control. 

Colloidal semiconductor nanocrystals are attracting growing attention as the building blocks for inexpensive, large-area, solution-processed solar cells. The advantages here are the scalable and controlled synthesis, an ability to be processed in solution, the broadband absorption, and the superior transport properties of traditional photovoltaic semiconductors. Solar cells that rely exclusively on colloidal nanocrystals have been anticipated theoretically58 and... 

Structural proof for the Herz salts (5//-pyrazolo[3,4-d]-l,2,3-dithiazol-2-ium chlorides) (29) rests on their UV spectra and chemical reactivity. Two bands were observed in the UV spectra of this series of compounds, one of which was very sensitive to the nature of the substituent at position 6. The similarity between these spectra and those for the known Herz salts of aniline derivatives suggest a similar chromophore <84JOCl224>. The stable sulfur-nitrogen radical (14) has a broadband absorption at 595.5 nm, giving it a blue color <89AG(E)920>. 

Results for up-pumping W(CO)6 with chirped pulse excitation were compared to excitation of the Tlu manifold using transform-limited pulses with center frequencies all tuned to the peak vibrational mode absorption frequency. Figure 3 shows transient broadband absorption spectra taken at 40 ps time delay for the three different pulse types. As depicted, one readily observes that the relative population amplitudes in the CO-stretch v = 1 (at 1970 cm-1) and v = 2 (at 1955 cm ) levels are strongly affected by the chirp of the excitation pulse. Excitation with negatively chirped... 

Each of these methods is based on the fact that broadband absorption is virtually the same at the resonance line as at a wavelength very close to the resonance line. If the background absorption is measured close to the resonance line then a correction can be made for the background absorption at the resonance line. 

Molecular compounds from the matrix which are not dissociated may, however, lead to broadband absorption spectra whereas small solid particles in the flame may diffuse the light over an extensive range of wavelengths. When these non specific absorptions are superimposed on the atomic absorption at the wavelength of the element to be determined, it is necessary to measure the non specific absorptions and correct the total absorption. 

Spectral interferences also result from the presence of combustion products that exhibit broadband absorption or particulate products that scatter radiation. Both reduce the power of the iraiismillcd beam and lead to positive analytical errors. When the source of these products is Ihe fuel and oxidant mixture alone, the analytical data c in be corrected by making absorption measurements while a blank is aspirated into the flame. Note that this correction must be used with both double-beam and single-beam inslrilmcnls because Ihe reference beam of a double-beam instrument does not pass through Ihe Hamc (see Figure 9-13b). 

The slii width is kepi sufficicnlly wide so ihai the fraction of the continuum source that is absorbed by the atoms of the sample is negligible. Therefore, Ihe alien-uation of the continuum source as it passes through the atomized sample reflects only the broadband absorption or sealiering by the sample matrix components. A background correclion is thus achieved. 

Pala, R.A., White, J., Barnard, E., Liu, J., Brongersma, M.L. Design of plasmonic thin-film solar cells with broadband absorption enhancements. Adv. Mater. 21, 3504-3509 (2009)... 

The vibrational spectra of the absorption bands of pure ZnFe204 and MnFe204 nanoparticles were observed at 388, and 541 cm-i, and at 404, 502, and 556 cm-ifor the samples calcined at 873 K (shown in Figure 21a and 21b). In these two ferrite nanoparticles, at the lower temperature of 873 K, however, there was still traces of broadband absorption peaks at 1497,... 

Carbon-rich compounds such as toluene and cyclohexane gave broadband absorption which exceeded the capacity of the deuterium background corrector. However, the solvents used in this study, methanol and benzene, were easily separated from the lead compounds. 

It is now well-established that the most general contribution in the FIR spectra of polymers in the range below tS0cm originates from the broadband absorption which is sometimes the background of the sharp lattice modes. Chantry and coworkers were the first to observe this broad and weak underlying absorption in the FIR spectra of PE, PP and TPX (a polyolefine based upon poly(4-methyl pentene-1) [2, 50]. It was supposed to be analogous to liquid-lattice type absorption observed in the far infrared spectra of polar and nonpolar liquids [51 -56]. 

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