Prism spectroscope

FIGURE 1.4 Separation ofspectral lines due to refraction in a prism spectroscope. 

Schuster method spect A method for focusing a prism spectroscope without using a distant object or a Gauss eyepiece. shus tar, meth-3d j... 

T. Melville noted in 1752 that sodium colours the flame of alcohol yellow, and A. S. Marggraf used this as a test to distinguish sodium from potassium salts. With an ordinary one-prism spectroscope, the spectrum appears with a single yellow fine corresponding with the D-line of the solar spectrum. This line really consists of two lines of wave-length 5896 and 5890. The emission spectrum of sodium shows many other lines of feeble intensity. In a salted Bunsen s flame, practically... 

Fig. 1. Simple prism spectroscope Collimator, C slit, S prism, P telescope, T and eyepiece for viewing spectrum. E...

Figure 24F-2 Bunsen burner of the type used in early spectroscopic studies with a prism spectroscope of the type used by Kirchhoff. (From H. Kayser, Handhuch der Spectroscopic. Stuttgart, Germany S. Hirzel Verlag GmbH Co., 1900.)...

In 1854, Kirchhoff found that each element has a unique spectrum. Later, Bunsen and Kirchhoff developed the prism spectroscope and used it to confirm their discovery of two new elements, cesium (in 1860) and rubidium (in 1861). 

Raman s earliest spectra were recorded with a small prism spectroscope equipped with a photographic plate. The spectra were excited with a mercury arc lamp, using a filter to select the Hg line of interest, and the samples were contained in a large spherical flask. A photograph of his spectrograph appears in the January 18, 1999 issue of C6cENews. 

The evolution of Raman instrumentation has been recently reviewed (Lewis, 2001a), from the first measurements by C.V. Raman, when the spectra were excited with a mercury lamp and recorded with a small prism spectroscope equipped with a photographic plate (Raman, 1928), to the new high resolution microscopes, in Raman scanning near-field optical microscopy (Adar, 2001). This review includes Raman microscopy (Baldwin, 2001), Raman imaging (Treado, 2001), the adaptation of Raman spectrometry to industrial environment (Slater, 2001), Raman spectroscopy of catalysts (Wachs, 2001) and process Raman spectroscopy (Lewis, 2001b). 

The shortest optical pulses actually used so far (1998) in ultrafast spectroscopic experunents were obtained by Shank and co-workers from an amplified CPM laser [ ]. In these extraordinary experiments, a sequence of a pair of prisms... 

The components of different frequency or wavelength are called lines because, in the early spectroscopic experiments, the radiation from the sample was passed through a slit and then through a prism the image of the slit was then focused on a photographic plate, where it appeared as a line. 

The very first spectroscopic instruments, from Newton s prism and pinhole to Frauenhofer s simple spectroscope, were constructed to observe luminescence. Even though the great sensitivity of luminescence detection seemed to promise that luminescence would become an important tool for chemical analysis, the fact is that absorption spectroscopy was the first spectroscopic technique to be widely used. At first glance, this may seem surprising since absorption spectroscopy is inherently less sensitive and had to await the development of more complex instrumentation, especially, electronically amplified detection. 

It is worth noting some historical aspects in relation to the instrumentation for observing phosphorescence. Harvey describes in his book that pinhole and the prism setup from Newton were used by Zanotti (1748) and Dessaignes (1811) to study inorganic phosphors, and by Priestley (1767) for the observation of electroluminescence [3], None of them were capable of obtaining a spectrum utilizing Newton s apparatus that is, improved instrumentation was required for further spectroscopic developments. Of practical use for the observation of luminescence were the spectroscopes from Willaston (1802) and Frauenhofer (1814) [13]. 

Many elements are present in the earth s crust in such minute amounts that they could never have been discovered by ordinary methods of mineral analysis. In 1859, however, Kirchhoff and Bunsen invented the spectroscope, an optical instrument consisting of a collimator, or metal tube fitted at one end with a lens and closed at the other except for a slit, at the focus of the lens, to admit light from the incandescent substance to be examined, a turntable containing a prism mounted to receive and separate the parallel rays from the lens and a telescope to observe the spectrum produced by the prism. With this instrument they soon discovered two new metals, cesium and rubidium, which they classified with sodium and potassium, which had been previously discovered by Davy, and lithium, which was added to the list of elements by Arfwedson. The spectroscopic discovery of thallium by Sir William Crookes and its prompt confirmation by C.-A. Lamy soon followed. In 1863 F. Reich and H. T. Richter of the Freiberg School of Mines discovered a very rare element in zmc blende, and named it indium because of its brilliant line in the indigo region of the spectrum. 

Spectroscope A device that uses a prism or diffraction grating to separate light into its color components. 

SPECTRO INSTRUMENTS. Spectro is used as a prefix for a wide assortment of analytical instruments. Spectro is derived from spectrum, which originally referred to the component colors that make up visible light, the so-called rainbow colors of violet, indigo, blue, green, yellow, orange, and red. A very simple device made up of a glass prism to break up sunlight into color bands is referred to as a spectroscope. Much more sophisticated instruments are available for manual manipulation and observation, which still rely on this basic, simple principle these are termed visual spectroscopes, and the field is called visual spectroscopy. 

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