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English for specific purposes (ESP) is a subset of English as a second or foreign language. It usually refers to teaching the English language to university students or people already in employment, with reference to the particular vocabulary and skills they need. As with any language taught for specific purposes, a given course of ESP will focus on one occupation or profession, such as Technical English, Scientific English, English for medical professionals, English for waiters, English for tourism, etc.1 Despite the seemingly limited focus, a course of ESP can have a wideranging impact, as is the case with Environmental English.
LOGO SPECTROSCOPY LECTURE : Võ GROUP : Uyên Vy Introduction SPECTROSCOPY Group – DHHC6B Before the beginning of the 20th century most quantitative chemical analyses used titrimetry as the analytical method analysts achieved highly accurate result But limited Other methods developed during this period extended quantitative analysis to include trace level analytes Colorimetry One example of an early colorimetric analysis is Nessler’s method Nessler’s method SPECTROSCOPY Group – DHHC6B The Nessler’s for ammonia It was first proposed in 1856 Nessler’s found that adding an alkaline solution of HgI2 and KI to a dilute solution of ammonia produced a yellow to reddish brown colloid with the color determined by the concentration of ammonia A comparison of the sample’s color to that for a series of standards was used to determine the concentration of ammonia Introduction SPECTROSCOPY Group – DHHC6B At the end 19th century, spectroscopy was limited to: The absorption Emission Scattering of UV/VIS Infrared electromagnetic radiation During the 20th , spectroscopy has been extended to include other form of electromagnetic radiation (photon spectroscopy) •X-rays •Microwaves •Radio waves •Energetic particles such as: electrons and ions Introductions SPECTROSCOPY Group – DHHC6B Introduction SPECTROSCOPY Group – DHHC6B Spectroscopy is used to qualitatively or quantitatively study the atoms or molecules, or to study physical processes The interaction of radiation with matter can cause redirection of the radiation and/or transitions between the energy levels of the atoms or molecule Introduction SPECTROSCOPY Group – DHHC6B A transition from a lower level to a higher level absorption ( transfer energy) A transition from a higher level to a lower level emission (transfer energy) Redirection of light due to its interaction with matter scattering (may or may not occur with transfer of energy) Absorption SPECTROSCOPY Group – DHHC6B Atoms or molecules absorb light a higher energy level Type of excitation depend on the wavelength of the light UV/Visible promoted electrons to higher orbital Infared excited vibrations Microwaves excited rolations Measuring the concentration of absorbing species in a sample is accomplished by Beer-Lambert Law SPECTROSCOPY Absorption Group – DHHC6B The absorption of light A function of wavelength Depend on its energy level structure An absorption spectrum Useful for indentifying of compounds Emission SPECTROSCOPY Group – DHHC6B 1.How is the emitting radiation? Atomic – emission spectroscopy and Atomic – fluorescence spectroscopy How is the flourescence of molecules and the phosphorescence of molecules?