Binding Energy Of Mg Research Articles

Influence of Mg doping on In adsorption and In incorporation in (In,Ga)N superlattices

We present a detailed investigation of the mechanisms at play for the incorporation of In and Mg on the GaN(0001) surface during plasma-assisted molecular beam epitaxy. First, we have studied the kinetics of In desorption in the presence of Mg either without or with N supply from the plasma cell by quadrupole mass spectrometry in the line of sight. Second, we have explored the effect of Mg doping at a different time along the cycle of (InN/GaN) supply repeated 10 times to form (In,Ga)N/GaN superlattices (SLs). By the complementary ex situ investigation of these SLs by x-ray diffraction and secondary ion mass spectrometry, we found that in the monolayer-thick (In,Ga)N layer, the In content was maximized when Mg was not supplied simultaneously to In, but it drastically decreased otherwise. In contrast, the Mg concentration strongly increased in the (In,Ga)N monolayers compared to the GaN barriers. We attribute this finding to the surfactant effect of In for Mg, which decreases the binding energy of Mg in GaN in the presence of N.

Photofragment imaging from mass-selected ions using a reflectron mass spectrometer I. Development of an apparatus and application to Mg+–Ar complex

The velocity and angular distributions of Mg+(2P3/2) produced by photolysis of Mg+–Ar complex at 4.66eV were observed using an apparatus set up for imaging fragment ions from mass-selected ions. The translational energy Et and the anisotropy parameter β were measured to be 640±80cm−1 and 1.03±0.05, respectively. The binding energy of Mg+–Ar in the ground state, estimated to be 1180±80cm−1, agreed with those reported in the literature. We have demonstrated that the recoil energy as small as 100meV can be resolved using this apparatus.

X-ray photoelectron spectroscopy studies of MgB2 for valence state of Mg

Core level X-ray photoelectron spectroscopy (XPS) studies have been carried out on polycrystalline MgB2 pellets over the whole binding energy range with a view to having an idea of the charge state of magnesium (Mg). We observe three distinct peaks in Mg 2p spectra at 49.3eV (trace), 51.3eV (major) and 54.0eV (trace), corresponding to metallic Mg, MgB2 and MgCO3 or, divalent Mg species, respectively. Similar trend has been noticed in Mg 2s spectra. The binding energy of Mg in MgB2 is lower than that corresponding to Mg(2+), indicative of the fact that the charge state of Mg in MgB2 is less than (2+). Lowering of the formal charge of Mg promotes the σ→π electron transfer in boron (B) giving rise to holes on the top of the σ-band which are involved in coupling with B E2g phonons for superconductivity. Through this charge transfer, Mg plays a positive role in hole superconductivity. B 1s spectra consist of three peaks corresponding to MgB2, boron and B2O3. There is also evidence of MgO due to surface oxidation as seen from O 1s spectra.

Magnesium salts and oxide: an XPS overview

XPS measurements have been performed on a series of Mg II salts (NO 3 −, CO 3 2−, SO 4 2−, Cl −, CH 3COO −), hydroxides and oxides, these latter compounds are both commercial and prepared in laboratory. The binding energy (BE) of the anionic partner in Mg II salts compares well in any case with literature data for the same anions in other alkaline and alkaline earth compounds. The BE of Mg II appears to be affected by the electroattractive nature of the parent anion. The Mg II spectra, in the case of MgO samples, are not influenced either by the nature of the oxide precursor salt or by the temperature of the oxide preparation (873 K, 1073 K, 1253 K). The BE of Mg 2p ranges between 49.9 eV and 50.2 eV. Oxygen spectra are regular and show the presence of the surface chemisorbed -OH component even at heating temperatures of 1473 K. The choice, as internal reference, of the hydrocarbon contaminant carbon peak is discussed, specifically, in the case of MgO samples with reference to specific lattice and surface properties of the oxide itself.

A determination of magnesium(1+)-ligand binding energies

Theoretical calculations employing large basis sets and including correlation are carried out for Mg(+) with methanol, water, and formaldehyde. For Mg(+) with ethanol and acetaldehyde, the trends in the binding energies are studied at the self-consistent-field level. The predictions for the binding energy of Mg(+) to methanol and water of 41 + or - 5 and 36 + or - 5 kcal/mol, respectively, are much less than the experimental upper bounds, of 61 + or - 5 and 60 + or - 5 kcal mol, determined by using photodissociation techniques. The theoretical results are inconsistent with the onset of Mg(+) production observed in the photodissociation experiments, as the smallest absorptions are calculated at about 80 kcal/mol for both Mg(+)-CH3OH and Mg(+)-H2O, and these transitions are to bound excited states. The binding energy for Mg(+) with formaldehyde is predicted to be similar to Mg(+)-H2O. The relative binding energies are in reasonable agreement with experiment. The binding energy of a second water molecule to Mg(+) is predicted to be similar to the first. This suggests that the reduced reaction rate observed for the second ligand is not a consequence of a significantly smaller binding energy, at least for the smaller ligards such as those considered in this work.

K-shell electron binding energy of metallic Mg and Ca.

Using total self-consistent-field (SCF) energy differences of small atomic clusters, simulating the metal environment, the \ensuremath{\Delta}SCF 1s binding energy is calculated. This \ensuremath{\Delta}SCF value, enhanced by atomic correlation and relativistic corrections, provides good values for the K-shell binding energy of Mg and Ca.

K-shell binding energy of Mg and Ca

Including many body, relativistic, and radiative effects, a theoretical value of 1311.47 eV has been obtained for the binding energy of Mg, and a value of 4047.84 eV for Ca. Two experimental values, 1311.4 and 1311.3 eV have been reported for Mg. Continuing our systematization of the effects of correlation upon this property, we note that the nonsatisfaction of Brillouin’s theorem for the final state plays an important role.

Temperature dependence of photoluminescence from Mg-implanted GaAs

Photoluminescence emission characteristics from Mg-implanted GaAs are presented for the temperature range T=4.2–293 °K. The emission due to recombination of free electrons with holes bound to neutral Mg acceptors is a dominant radiative process in heavily implanted samples at temperatures T≲210 °K. Changes in the emission energies and intensities as a function of temperature lead to the determination of the binding energy of Mg as 28±2 meV. The donor-acceptor pair band involving Mg, which has a large energy shift with the change of excitation intensity, shows the lower-energy shift with an increase of temperature in the range T=4.2–50 °K. This is explained by associating deeper donor states than the hydrogenic donors to the donor-acceptor pair band. Depth dependence of the donor-acceptor pair and the free-electrons to the neutral Mg acceptor bands show a deep penetration of Mg acceptors.