Mercury metastable

Essentially, an ultrashort laser pulse associates two colliding reactants to a new product. In the present case, a metastable excimer Hg2 is formed from two mercury atoms. This photoassociation process may be considered as the reverse of photodissociation. From a theoretical point of view, the important difference between processes (2) and (3) is that the unimolecular photodissociation (2) starts from bound states, whereas the bimolecular photoassociation (3) starts from continuum states, as demonstrated by model simulations in Fig. 1 (supported by Deutsche Forschungsgemeinschaft). 

PENNING EFFECT. An increase in the effective ionization rate of a gas due to the presence of a small number of foreign metastable atoms. For instance, a neon atom has a metastable level at 16.6 volts and if there are a few neon atoms in a gas of argon which has an ionization potential of 15.7 volts, a collision between the neon metastable atom with an argon atom may lead to ionization of the argon. Thus, the energy which is stored in the metastable atom can be used to increase the ionization rate. Other gases where this effect is used are helium, with a metastable level at 19.8 volts, and mercury, with an ionization level at 10.4 volts. 

CH3C1 (90, 34 and 8 A2, respectively). These values suggest a similarity between these reactions and the corresponding ground state alkali atom reactions. The ionisation potential of Hg (3P2) is 4.974eV which is similar to those for the alkali atoms and so an electron jump mechanism is proposed for these chemiluminescent reactions of Hg (3P2 ) In contrast, the reaction of another spin-orbit state of metastable mercury with bromine, Hg (3P0) + Br2, has a much smaller chemiluminescent cross section [3 A2 compared with 150 A2 for Hg (3P2) + Br2] [406], which cannot be reconciled with an electron jump, suggesting the existence of a barrier to reaction of Hg (3P0) which is not present in the case of Hg(3P2). 

Mercury may be easily excited to the 6 aP2 state by 2537-A radiation or by electron impact, and the excitation energy may be removed partly or totally in collisions with unexcited atoms or molecules. It is generally recognized that collisions with noble-gas atoms do not result in excitation transfer to the 6 3P0 metastable state or in quenching to the 6 S, ground state [90-92] and that such processes can be accomplished only in collisions with molecules... 

The Hg-0 distances within the chains is 2.03 A while the closest interchain distance is 2.82 A. If a Hg+ salt solution is treated with warm, aqueous NaOH for several hours, metastable crystals of HgO form that have the hexagonal cinnabar (HgS) sfructure. Again the basic building blocks are O-Hg-O chains but now they wrap in a helical fashion and are cross-linked to other chains by Hg-O bonds to form a highly distorted octahedron of oxygens about each mercury with the motif of 2 short linear Hg bonds being maintained. 

The equilibrium constant of reaction (1), K = [Cu ][Cu ]/[Cu ], is of the order of 10 thus, only vanishingly small concentrations of aquo-copper(I) species can exist at equilibrium. However, in the absence of catalysts for the disproportionation—such as glass surfaces, mercury, red copper(I) oxide (7), or alkali (311)—equilibrium is only slowly attained. Metastable solutions of aquocopper(I) complexes may be generated by reducing copper(II) salts with europium(II) (113), chromium(II), vanadium(II) (113, 274), or tin(II) chloride in acid solution (264). The employment of chromium(II) as reducing agent is best (113), since in most other cases further reduction to copper metal is competitive with the initial reduction (274). 

Mercury (I I) sulphide, HgS, exists in both zinc-blende and rock-salt structures, the red, hexagonal cinnabar, s.g. 8.18, being the stable and common form the metastable, black, cubic metacinnabar, s.g. 7.60, is rare. Mercury(I) sulphide is unknown. 

Callear and Norrish have used the technique to study the rise and decay of metastable Hg (6 Pq) atoms populated from Hg (6 Pi) atoms excited in mercury vapour by the flash. A number of transitions in absorption from Hg (6 Pq) were identified, and the 6 - 6 ae at 2967 A was chosen for plate photometry. 

K.Ohmori, T.Kurosawa, H.Chiba, M.Okunishi, K.Ueda, Y.Sato, A. Devdariani, and E.E.Nikitin, Far-wing excitation study on the transition region of the metastable mercury atom collisions Hg(6 P2)+N2 and CO, Chem. Phj. Lett. 315, 411 (1999)... 

From Vukalovich, Ivanov, Fokin, and Yakovlev, Thermophysical Properties of Mercury, Standartov, Moscow, 1971. For the saturated liquid the specific volume at 203.15 K is 7.26239 x 10 m Vkg, etc. All the tabular values for 203.15 K, 213.15 K, 223.15 K, and 233.15 K represent a metastable equilibrium between the subcooled liquid and the saturated vapor. 

Kiselev, S. B., and Ely, J. F. (2001) Curvature effect on the physical boundary of metastable states in liquids, PhysicaA 299, 357-370 Roedder, E. (1967) Metastable superheated ice in liquid-water inclusions under high negative pressure, Science 155, 1413 Shmulovich, K. 1., Mercury, E., Ramboz, C., and El Mekki, M. (2008) Metastable water in synthetic fluid inclusions in quartz, in book Metastable state and phase transitions memory of P.Scripov), Yekaterinburg, v. 8, p. 210-219 (in Russian)... 

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