ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

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Metal adsorption calorimetry and adhesion energies on clean single-crystal surfaces (1997)

Stuckless, J. T. ; Starr, D. E. ; Bald, D. J. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 107 (1997), S. 5547-5553

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: The heats of adsorption of metals have been measured calorimetrically for the first time on clean, single-crystalline surfaces. A pulse of metal vapor from a chopped atomic beam adsorbs onto an ultrathin single crystal's surface, causing a transient temperature rise. This heat input is detected by a pyroelectric polymer ribbon, which is gently touched to the back of the crystal during calorimetry. The sticking probability is measured by detecting the reflected fraction mass spectroscopically. The differential heat of adsorption is thus measured as a detailed function of coverage up through multilayer coverages. The integral heat of adsorption also provides the adhesion energy of the metal film, if the surface free energy of the clean metal surface is known. Adsorption and adhesion energies for metals (Pb or Cu) on clean Mo(100) and on well-defined surface oxides of Mo(100) and W(100) are reported. © 1997 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.474230

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2

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ELECTRON SHARING ABILITY OF ORGANIC RADICALS. VI. ALPHA-SUBSTITUTED PYRROLINES AND PYRROLIDINES (1932)

Starr, D. F. ; Bulbrook, Helen ; Hixon, R. M.

s.l. : American Chemical Society

Journal of the American Chemical Society 54 (1932), S. 3971-3976

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ISSN: 1520-5126

Source: ACS Legacy Archives

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1021/ja01349a023

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3

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Microcalorimetric measurements of the heat of adsorption of Pb on well-defined oxides: MgO(100) and p(2×1)-oxide on Mo(100) (2001)

Starr, D. E. ; Bald, D. J. ; Musgrove, J. E. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 114 (2001), S. 3752-3764

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: The energetics of Pb film grown at 300 K on two well-defined oxides [a MgO(100) thin film and a p(2×1)-oxide on Mo(100)] have been measured using single-crystal adsorption microcalorimetry. The evolution of the film morphology was followed using Auger electron spectroscopy (AES). An initial heat of adsorption of 103 kJ/mol is observed for the Pb/MgO(100) system. Auger results indicate that this is due to the formation of an ∼20 atom Pb island in the first pulse of Pb gas incident on the MgO(100) surface. This allows the extraction of a Pb–MgO(100) bond energy of ∼32±2 kJ/mol in the small two-dimensional particles formed in the first pulse. As more Pb is deposited onto the MgO(100) surface, the Pb forms three-dimensional islands. The integral of the heats of adsorption up to high coverage indicates an adhesion energy of 76.5±∼20 μJ/cm2 for large 3D Pb particles to the MgO(100) substrate. This indicates a Pb–MgO(100) bond energy of 49±13 kJ/mol at the 3D interface. Similar analyses of the Pb/p(2×1)-oxide on Mo(100) surface give an initial heat of adsorption of 146.2 kJ/mol and an adhesion energy of 82.5±20 μJ/cm2 for thick Pb films. This indicates a bond energy of 52±12 kJ/mol for a Pb atom to this surface at the interface of a thick Pb film. The metal's sticking probabilities as a function of coverage and the coverage-dependent changes in optical reflectivity were measured. For the Pb/MgO(100) system, an initial sticking probability of 0.70 at 300 K was observed, whereas for the Pb/p(2×1)-oxide on Mo(100) surface unit sticking probability was observed. The relationship between these quantities and the adsorption energetics is discussed. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1337097

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4

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Erratum: "Microcalorimetric measurements of the heat of adsorption of Pb on well-defined oxides: MgO(100) and p(2×1)-oxide on Mo(100)" [J. Chem. Phys. 114, 3752 (2001)] (2001)

Starr, D. E. ; Bald, D. J. ; Musgrove, J. E. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 115 (2001), S. 6798-6798

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1404394

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5

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An infrared flash contemporaneous with the γ-rays of GRB 041219a (2005)

Blake, C. H. ; Starr, D. L. ; Falco, E. E. ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 435 (2005), S. 181-184

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] The explosion that results in a cosmic γ-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/nature03520

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6

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Turbulent heat transfer from a sparsely vegetated surface: Two-component representation (1993)

Otterman, J. ; Novak, M. D. ; Starr, D. O. C.

Springer

Boundary layer meteorology 64 (1993), S. 409-420

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ISSN: 1573-1472

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract The conventional calculation of heat fluxes from a vegetated surface, involving the coefficient of turbulent heat transfer, which increases logarithmically with surface roughness (commonly taken as about 0.12 of the plant height), appears inappropriate for highly structured surfaces such as desertscrub or open forest. An approach is developed here for computing sensible heat flux from sparsely vegetated surfaces, where the absorption of insolation and the transfer of absorbed heat to the atmosphere are calculated separately for the plants and for the soil. This approach is applied to a desert-scrub surface for which the turbulent transfer coefficient of sensible heat flux from the plants is much larger than that from the soil below, as shown by an analysis of plant, soil and air temperatures measured in an animal exclosure in the northern Sinai. The plant density is expressed as the sum of products (plant-height) x (plant-diameter) of plants per unit horizontal surface area (the dimensionless silhouette parameter of Lettau). The solar heat absorbed by the plants is assumed to be transferred immediately to the airflow. The effective turbulent transfer coefficientk g-eff for sensible heat from the desert-scrub/soil surface computed under this assumption increases sharply with increasing solar zenith angle, as the plants absorb a greater fraction of the incoming irradiation. The surface absorptivity (the co-albedo) also increases sharply with increasing solar zenith angle, and thus the sensible heat flux from such complex surfaces (which include open forests) is a much broader function of time of day than when computed under constantk g-eff and constant albedo assumptions. The major role that desert-fringe plants play in the genesis of convection and advection cannot be evaluated properly in the conventional calculations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00711708

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7

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An increase of early rains in Southern Israel following land-use change? (1990)

Otterman, J. ; Manes, A. ; Rubin, S. ; [et al.]

Springer

Boundary layer meteorology 53 (1990), S. 333-351

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ISSN: 1573-1472

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract The October rains (at the onset of the rainy season that extends to April) in southern Israel have steeply increased in the last quarter century relative to the prior two decades. A less pronounced, but appreciable, increase is noted for the rest of the rainy season. This apparent reversal of desertification is attributed here to land use changes. Afforestation, increased cultivation and limitations on grazing after the establishment of the State of Israel resulted in an increased vegetation cover over the inherently high-albedo soils in this region (an area of ∼104 km2). The changes are shown in a July 1985 Landsat image of the area. The increase in precipitation is specifically attributed to intensification of the dynamical processes of convection and advection resulting from plant-induced enhancement of thedaytime sensible heat flux from the generally dry surface. This enhancement results both from the reduced surface albedo and the reduced soil heat flux (reduced day-to-night heat storage in the soil) in October when insolation is strong. Stronger daytime convection can lead to penetration of the inversions capping the planetary boundary layer (which are weaker in October than in summer) while strengthened advection (sea breeze) can provide moist air from the warm Mediterranean Sea. This suggested mechanism is consistent with previous studies showing that the autumn rains in southern Israel exhibit convective mesoscale characteristics and occur predominantly in the daytime. However, other causes, such as a shift in the synoptic-scale circulation, cannot be ruled out at this stage.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02186093

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8

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Relationship of Late-Winter Temperatures in Europeto North Atlantic Surface Winds: A Correlation Analysis (1999)

Otterman, J. ; Atlas, R. ; Ardizzone, J. ; [et al.]

Springer

Theoretical and applied climatology 64 (1999), S. 201-211

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ISSN: 1434-4483

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Summary The relationship between European surface temperature and winds over the eastern North Atlantic are investigated for the years 1988 to 1997. Daily Special Sensor Microwave Imager SSM/I observations are used to evaluate a monthly surface wind index that quantifies the influence of southwesterly flow. Our wind index and the monthly-mean surface-air temperatures in late winter and early spring over France and northern-latitude Europe are highly correlated. In February, the year-to-year increases/decreases match every year for France (correlation of 0.82 with the Index); and every year with just one exception for Europe (correlation with the Index of 0.76 for a longitudinal strip through Europe 45–50° N, and 0.73 for the 50–60° N strip). In March, the increases/decreases of the wind Index and of the temperatures for France also match, but the correlation with the Index is lower, 0.65. The high correlation between our Index and the large interannual fluctuations in the monthly temperature in late winter and early spring indicate that the onset of the spring conditions in Europe is significantly influenced by the wind patterns over the eastern North Atlantic. Coinciding with the fluctuations from warm-Europe/high-Index winter to the opposite conditions, we observe “seesaw” effects, fluctuations over the North Atlantic, in opposite directions in the east (25–5° W), and the west (65–45° W). In the low-Index years we find that: (a) the surface-air temperatures in the west are appreciably higher than in the east (but slightly lower in the high-Index year), and (b) the difference between the 500 mb meridional wind in the west and that in the east is positive and large, exceeding 10 m s−1 (but it becomes negative and small in the high-Index years). The “seesaw” effects suggest that a positive feedback exits between these cross-Atlantic temperature differences and the surface winds.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s007040050123

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