Mercury, atomic wavelength

This applies solely to mercury as it is the only analyte that has an appreciable atomic vapour pressure at room temperature. The 253.7 nm line is usually used for mercury atomic absorption, but the transition is spin forbidden, and relatively insensitive. The 184.9 nm line is potentially 20-40 times more sensitive, but at this wavelength most flame gases and the atmosphere absorb strongly. Thus, flame methods for mercury are not noted for their sensitivity (typical flame defection limits are in the range 1-0.1 pg ml-i). If chemical reduction is employed, mercury can be brought into the vapour phase without the need to use a flame, and defection limits are dramatically improved. 

A particular transition in a mercury atom emits a photon of blue light with a wavelength of 435.8 nm. What is the energy change of the atom ... 

Mercury s atomic emission spectrum is shown below. Estimate the wavelength of the orange line. What is its frequency What is the energy of an orange photon emitted by the mercury atom ... 

The first two excitation voltage thresholds in the Franck-Hertz study of mercury vapor were found at 4.9 and 6.7 V. Calculate the wavelength of light emitted by mercury atoms after excitation past each of these thresholds. 

Excited mercury atoms emit light strongly at a wavelength of 454 nm. This emission predominates when mercury atoms are excited in a flame. Predict the color of the flame. 

The importance of photosensitization derives f rom the f act that reaction is produced in the presence of the sensitizer in circumstances where the direct photochemical dissociation is not possible. The example just cited is a case in point. Radiation of wavelength 253.7 nm was absorbed by a mercury atom. The excited mercury atom dissociated a molecule of hydrogen by transferring the excitation energy in a collision. The mercury atom had 471.5 kJ of this 432.0 kJ were needed for the dissociation 39.5 kJ are left over and go into additional translational energy of the two hydrogen atoms and the mercury atom. If the attempt is made to dissociate H2 directly by the process... 

A luminescent lamp is filled with a noble gas at a pressure of 400 Pa, containing 0.8 Pa mercury. In the dischaige the mercury atoms ate excited. When they return to the ground state, they emit (mainly) ultraviolet radiation. About 85% of the emitted radiation is at 254 nm and 12% at 185 nm. The remaining 3% is found in the longer wavelength ultraviolet and visible region (365, 405, 436 and 546 run). 

A mercury atom emits light at many wavelengths, two of which are at 435.8 and 546.1 nm. Both of these transitions are to the same final state, (a) What is the energy difference between the two states for each transition (b) If a transition between the two higher energy states could be observed, what would be the frequency of the light ... 

Energy level diagram for mercury (Hg) atoms showing the most prominent absorption and emission lines. The numbers accompanying the arrows are the wavelengths in nanometers (nm) of the photons associated with these transitions. 

Since our main objective was to remove all the chlorine and hydrogen atoms from the polymer chain, C-PVC films were further exposed to the UV radiation of the medium pressure mercury-lamp. This led to a dark brown material w.hich was found to be unable to carry an electrical current, even after extended irradiation time. Therefore we turned to a powerful laser source, a 15 W argon ion laser tuned to its continuous emission at 488.1 nm. At that wavelength, the degraded polymer film absorbs about 30 % of the incident laser photons. The sample was placed on a X-Y stage and exposed to the laser beam at scanning rates in the range of 1 to 50 cm s, in the presence of air. 

Mercury is most accurately determined by the cold vapor atomic absorption spectroscopic method. The instrument is set at the wavelength 253.7 nm. The metal, its salts and organic derivatives in aqueous solution can be measured by this method. The solution or the solid compounds are digested with nitric acid to convert into water-soluble mercury(ll) nitrate, followed by treatment with potassium permanganate and potassium persulfate under careful heating. The excess oxidants in the solution are reduced with NaCl-hydroxylamine sulfate. The solution is treated with stannous chloride and aerated. The cold Hg vapor volatdizes into the absorption cell where absorbance is measured. 

---