Deuteriumation from subsurface deuterium

SCHEME 1.4 Depiction of deuterium attacking from the subsurface through a three-fold hollow site. The second (lower) layer of metal atoms is not shown. 

FIGURE 2.27 Two possible mechanisms to explain deuterium distributions resulting from deuteriumation and exchange of methyl vinyl ketone. Deuterium is assumed to move subsurface and to attack adsorbed carbons from threefold hollows. Path A multiple exchange by repeated addition-rotation-abstraction at the [3-carbon (classic mechanism) path B I -A hydrogen shift followed by desorption as enol. 

The substitution of the H(D)-termination by the D+CH ) in the solution at the extreme cathodic potential was confirmed from the above-mentioned results[24]. The hydrogen evolution at the B-doped diamond electrode does proceed via the carbon radical formation at the surface, as shown in eq.(7.l). However, it is difficult to estimate the surface concentration of the substituted sites due to the lack of the inspected correlation between the yield obtained and the surface concentration of the surface hydrogen. The absorption of atomic hydrogen or deuterium in the subsurface and bulk of the B-doped diamond may also confuse this problem [25, 26]. Since the surface roughness affects the yield, TOF ESD measurements at epitaxially grown B-doped diamond single crystalline electrodes [27, 28] are desirable in order to estimate the kinetics of the cathodic substitution of the surface hydrogen. 

Waite et al., 2009 [350] found that ammonia is present in the plume, along with various organic compounds, deuterium and, very probably, " Ar. The presence of ammonia provides strong evidence for the existence of at least some liquid water, given that temperatures in excess of 180 K have been measured near the fractures from which the jets emanate. Ammonia (together with methanol and salts) acts as an antifreeze that permits the existence of liquid water down to temperatures as low as 176 K. Schneider et al., 2010 [295] searched for sodium in Enceladus water plumes. The lack of observable sodium in the vapor is consistent with a deep ocean, a freshwater reservoir, or ice. The plume particles are the most important source for particles in Saturn s E-ring. The observations are consistent with a subsurface ocean in contact with its rock core. There is no atomic sodium in the vapor however it is present in salts in Saturn s E ring (see also Spencer, 2(X)9 [314]). 

---