Advances in understanding and treating ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurocognitive behavioral developmental disorder most commonly seen in childhood and adolescence, which often extends to the adult years. Relative to a decade ago, there has been extensive research into understanding the factors underlying ADHD, leading to far more treatment options available for both adolescents and adults with this disorder. Novel stimulant formulations have made it possible to tailor treatment to the duration of efficacy required by patients, and to help mitigate the potential for abuse, misuse and diversion. Several new non-stimulant options have also emerged in the past few years. Among these, cognitive behavioral interventions have proven popular in the treatment of adult ADHD, especially within the adult population who cannot or will not use medications, along with the many medication-treated patients who continue to show residual disability

On the adsorption sites for CO on the Rh(111) single crystal surface

High resolution photoemission applied to the C 1s and Rh 3d core levels has been used to investigate the adsorption sites at low temperature of CO on the Rh(111) single crystal surface as a function of CO coverage. Two different sites are found to be occupied by the CO molecules. At coverages up to 0.5 monolayers the majority of the molecules are found to adsorb in on-top sites whereas at higher coverages three-fold hollow sites become increasingly populated. The different C 1s binding energy of the CO molecules in these two sites makes it possible to measure diffraction induced intensity variations versus photon energy in a site specific manner. The saturation (2 x 2)-3CO structure formed at a coverage of 0.75 monolayers is argued to contain one on-top and two three-fold hollow molecules per unit cell

Adsorption sites in coadsorption systems determined by photoemission spectroscopy : K and CO coadsorbed on Rh(111)

The adsorption sites of coadsorbed K and CO on the Rh(111) surface have been determined using high-resolution core-level spectroscopy, low-energy electron diffraction and site-resolved photoelectron diffraction. For both a (2 × 2)-2CO-1K and a (2√3 × 2√3)-6CO-1K structure, we find that the CO molecules occupy threefold hollow sites and the K atoms on-top sites, contrary to the adsorption sites of K (threefold hollow site) and CO (on-top site below 0.5 monolayers) if adsorbed alone on Rh(111). Deposition of K onto a CO precovered surface is found to induce large shifts towards lower binding energy of the C and O 1s core levels (∼0.7 eV for C 1s and ∼1.5 eV for O 1s). The major part of these shifts is shown to arise from the K-induced site change of the CO molecules. This finding may be of importance in the interpretation of XPS data of related co-adsorption systems. Finally, it is suggested that the C and O 1s binding energies provide useful fingerprints of the CO adsorption site also for co-adsorption systems

Adsorption sites in O and CO coadsorption phases on Rh(111) investigated by high-resolution core-level photoemission

High-resolution core-level spectroscopy is used in combination with low-energy electron diffraction (LEED) and photoelectron diffraction to identify the adsorption sites for three different coadsorbed phases consisting of ordered overlayers of oxygen coadsorbed with CO on the Rh(111) single-crystal surface. The three ordered overlayer structures, which may be denoted as 2O + CO/Rh(111), O + CO/Rh(111) and O+2CO/Rh(111), all show (2 × 2) LEED patterns. In the 2O + CO and O + CO phases the CO molecules are found to occupy only on-top sites while the O + 2CO phase shows CO molecules in both on-top and three-fold hollow sites. In all cases the oxygen atoms are found in three-fold hollow sites. For the O + CO and O + 2CO phases our results confirm previous determinations by LEED, while the 2O + CO phase has not been observed before on Rh(111). The core-level binding energies of the C 1s and O 1s core levels for both adsorbates are characteristics of the adsorption site and are very close to the binding energies found for the pure cases of only oxygen or CO adsorbed on Rh(111). In the coadsorption phases we find that the interaction between the adsorbates has only a minor influence on the core-level binding energies. For the O + 2CO/Rh(111) coadsorption phase we find that a full CO coverage is not obtained; less than 80% of the unit cells contain two CO molecules, in line with previous findings