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Ion-molecule complexes of the form Mg(H2O)Ar(sub n)(super +) (n=1-8) are produced by laser vaporization in a pulsed-nozzle cluster source and are further studied with infrared photodissociation spectroscopy in the O-H stretch region. The combined spectroscopic and theoretical studies reveal the presence of multiple isomeric structures at each cluster size as the argon atoms gather around the Mg+(H2O) unit.

Creeping bentgrass (Agrostis stolonifera L.) golf greens are often shaded by trees and surrounded by shrubs or brush that restrict airflow. The objective of this study was to compare and independently evaluate turfgrass responses to light reduction and airflow restriction in 'L9Y and 'SR1020' creeping bentgrass. Artificial structures (122 by 122 cm) were assembled from polyvinyl chloride (PVC), and covered with black, woven polyester shade cloth (80% light reduction) to provide treatment effects. Shade doth was applied to the structures to reduce irradiance and allow airflow or reduce airflow and allow irradiance. Plots were rated monthly for canopy, soil, and air temperature, visual color, density, and disease, soil moisture, root mass, and root glucose and fructose. Canopy and soil temperatures were lower in shade than in airflow restriction and uncovered, unsurrounded control tuff. Canopy temperature was higher in airflow restriction than control but soil temperatures did not differ. Both shade and airflow restriction had a negative effect on turf color in L93. Airflow restriction caused a greater reduction in mean color rating than shade in SR1020 but shade color did not differ from control. Turf density declined in both cultivars due to both airflow restriction and shade compared with control. Air restriction reduced density more than shade in SR1020 but not in L93. The severity of brown patch (caused by Rhizoctonia solani Kuhn) and dollar spot (caused by Sclerotinia homoeocarpa F.T. Bennett) in shade was less than in airflow restriction in both cultivars and less than control in SR1020. Soil moisture did not differ among treatments. Root mass was affected by both shade and airflow restriction in both cultivars and declined more rapidly in shade than in airflow restriction. Root glucose and fructose were not significantly affected by treatments., CREEPING BENTGRASS is the most widely used cool season grass for golf greens, although it may decline because of intense management and environmental stresses during the summer months. A reduction [...]

Research was conducted to examine a new method of generating multiply charged metal-containing clusters in the gas phase such as Cu(II), Mg(II) and Sr(II). In an attempt to develop stable gas-phase complexes with Ag(II), various diverse ligands were investigated. Many of the ligands could not stabilize the ion due to the property of silver of having the highest second ionization energy of any metal. However, results demonstrate that many of the silver complexes that were confirmed through collisional activation, conform to expectations with regards to coordination numbers.

Ni+(CO2)n and NiO2+(CO2)m ion-molecule complexes are mass-selected and studied with infrared photodissociation spectroscopy. Dissociation is inefficient until clusters exceed a critical size of n=4 for Ni+(CO2)n and m=2 for NiO2(CO2)m+. Dissociation of larger clusters terminates at these same critical sizes. Just beyond the critical size, the infrared spectra exhibit new vibrational bands associated with ligands not coordinated to the metal. These observations indicate that the coordination of Ni+ ions with respect to CO2 binding is exactly four, and that the coordination for NiO2+ is two CO2 ligands, making the overall coordination around the metal the same value of four. [Copyright &y& Elsevier]