A Stable Pure Hydroxyl Layer on Pt{110}-(1×2)

2009 ◽  
Vol 113 (52) ◽  
pp. 21755-21764 ◽  
Author(s):  
A. Shavorskiy ◽  
T. Eralp ◽  
M. J. Gladys ◽  
G. Held
Keyword(s):  
Hydroxyl Layer

scholarly journals Stability of temperatures from TIMED/SABER v1.07 (2002–2009) and Aura/MLS v2.2 (2004–2009) compared with OH(6-2) temperatures observed at Davis Station, Antarctica

2010 ◽  
Vol 10 (9) ◽  
pp. 21547-21565 ◽  
Author(s):  
W. J. R. French ◽  
F. J. Mulligan
Keyword(s):  
Cold Bias ◽  
Spatial And Temporal Scales ◽  
Ground Station ◽  
Volume Emission ◽  
The Difference ◽  
Miss Distance ◽  
Hydroxyl Layer ◽  
The Impact ◽  
Long Term Studies

Abstract. Temperature profiles from two satellite instruments – TIMED/SABER and Aura/MLS – have been used to calculate hydroxyl-layer equivalent temperatures for comparison with values measured from OH(6-2) emission lines observed by a ground-based spectrometer located at Davis Station, Antarctica (68° S, 78° E). The profile selection criteria – <500 km from the ground station and solar zenith angles >97° – yielded a total of 2359 SABER profiles over 8 years (2002–2009) and 7407 MLS profiles over 5.5 years (2004–2009). The availability of simultaneous OH volume emission rate (VER) profiles from the SABER (OH-B channel) enabled an assessment of the impact of several different weighting functions in the calculation of OH-equivalent temperatures. The maximum difference between all derived hydroxyl layer equivalent temperatures was less than 3 K. Restricting the miss-distance and miss-time criteria showed little effect on the bias, suggesting that the OH layer is relatively uniform over the spatial and temporal scales considered. However, a significant trend was found in the bias between SABER and Davis OH of ~0.7 K/year over the 8-year period with SABER becoming warmer compared with the Davis OH temperatures. In contrast, Aura MLS exhibited a cold bias of 9.9 ± 0.4 K compared with Davis OH, but importantly, the bias remained constant over the 2004–2009 year period examined. The difference in bias behaviour of the two satellites has significant implications for multi-annual and long-term studies using their data.

scholarly journals Stability of temperatures from TIMED/SABER v1.07 (2002–2009) and Aura/MLS v2.2 (2004–2009) compared with OH(6-2) temperatures observed at Davis Station, Antarctica

2010 ◽  
Vol 10 (23) ◽  
pp. 11439-11446 ◽  
Author(s):  
W. J. R. French ◽  
F. J. Mulligan
Keyword(s):  
Cold Bias ◽  
Spatial And Temporal Scales ◽  
Ground Station ◽  
Volume Emission ◽  
The Difference ◽  
Miss Distance ◽  
Hydroxyl Layer ◽  
The Impact ◽  
Long Term Studies

Abstract. Temperature profiles from two satellite instruments – TIMED/SABER and Aura/MLS – have been used to calculate hydroxyl-layer equivalent temperatures for comparison with values measured from OH(6-2) emission lines observed by a ground-based spectrometer located at Davis Station, Antarctica (68° S, 78° E). The profile selection criteria – miss-distance <500 km from the ground station and solar zenith angles >97° – yielded a total of 2359 SABER profiles over 8 years (2002–2009) and 7407 MLS profiles over 5.5 years (2004–2009). The availability of simultaneous OH volume emission rate (VER) profiles from the SABER (OH-B channel) enabled an assessment of the impact of several different weighting functions in the calculation of OH-equivalent temperatures. The maximum difference between all derived hydroxyl layer equivalent temperatures was less than 3 K. Restricting the miss-distance and miss-time criteria showed little effect on the bias, suggesting that the OH layer is relatively uniform over the spatial and temporal scales considered. However, a significant trend was found in the bias between SABER and Davis OH of ~0.7 K/year over the 8-year period with SABER becoming warmer compared with the Davis OH temperatures. In contrast, Aura/MLS exhibited a cold bias of 9.9 ± 0.4 K compared with Davis OH, but importantly, the bias remained constant over the 2004–2009 year period examined. The difference in bias behaviour of the two satellites has significant implications for multi-annual and long-term studies using their data.

Mechanism of the hydrogen-oxygen reaction on platinum films from surface potential measurements

1975 ◽  
Vol 343 (1635) ◽  
pp. 477-488 ◽  
Keyword(s):  
Water Vapour ◽  
Surface Potential ◽  
Hydrogen Gas ◽  
Surface Sites ◽  
Surface Potential Measurements ◽  
Oxygen Gas ◽  
Experimental Values ◽  
Hydroxyl Layer ◽  
Oxygen Reaction ◽  
Supported Metal

The surface-potential changes that occur during the reaction of hydrogen and oxygen on an evaporated platinum film have been recorded by means of the static capacitor method. A sequence of reaction steps has been proposed for the reactions of hydrogen gas with an oxygen-adatom monolayer, and oxygen gas with a hydrogen-adatom layer. The chemisorption of water vapour, by both a clean film and one covered with an oxygen or hydrogen monolayer, has also been investigated. From separate measurements of the s.p. of monolayers of oxygen, hydrogen and water, that of a hydroxyl layer has been calculated; from these values and the measured uptakes of oxygen and hydrogen, the complete s.p. plots have been calculated with consistent agreement with the experimental values. The presence of groups of surface sites of different reactivity previously suggested is confirmed. Explanations for the lack of stoichiometry of the hydrogen titration results reported in the literature and for lack of agreement with infrared results on oxide-supported metal are outlined.

scholarly journals c(2×2)Water-Hydroxyl Layer on Cu(110): A Wetting Layer Stabilized by Bjerrum Defects

2011 ◽  
Vol 106 (4) ◽  
Author(s):  
Matthew Forster ◽  
Rasmita Raval ◽  
Andrew Hodgson ◽  
Javier Carrasco ◽  
Angelos Michaelides
Keyword(s):  
Wetting Layer ◽  
Hydroxyl Layer

scholarly journals Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78° N, 16° E)

2009 ◽  
Vol 27 (11) ◽  
pp. 4197-4205 ◽  
Author(s):  
F. J. Mulligan ◽  
M. E. Dyrland ◽  
F. Sigernes ◽  
C. S. Deehr
Keyword(s):  
Emission Rate ◽  
Winter Season ◽  
Extended Period ◽  
Emission Layer ◽  
Atmospheric Extinction ◽  
Volume Emission ◽  
Km Value ◽  
Hydroxyl Layer ◽  
Peak Emission ◽  
Layer Peak

Abstract. Measurements of hydroxyl nightglow emissions over Longyearbyen (78° N, 16° E) recorded simultaneously by the SABER instrument onboard the TIMED satellite and a ground-based Ebert-Fastie spectrometer have been used to derive an empirical formula for the height of the OH layer as a function of the integrated emission rate (IER). Altitude profiles of the OH volume emission rate (VER) derived from SABER observations over a period of more than six years provided a relation between the height of the OH layer peak and the integrated emission rate following the procedure described by Liu and Shepherd (2006). An extended period of overlap of SABER and ground-based spectrometer measurements of OH(6-2) IER during the 2003–2004 winter season allowed us to express ground-based IER values in terms of their satellite equivalents. The combination of these two formulae provided a method for inferring an altitude of the OH emission layer over Longyearbyen from ground-based measurements alone. Such a method is required when SABER is in a southward looking yaw cycle. In the SABER data for the period 2002–2008, the peak altitude of the OH layer ranged from a minimum near 76 km to a maximum near 90 km. The uncertainty in the inferred altitude of the peak emission, which includes a contribution for atmospheric extinction, was estimated to be ±2.7 km and is comparable with the ±2.6 km value quoted for the nominal altitude (87 km) of the OH layer. Longer periods of overlap of satellite and ground-based measurements together with simultaneous on-site measurements of atmospheric extinction could reduce the uncertainty to approximately 2 km.

scholarly journals Hydroxyl layer: Mean state and trends at midlatitudes

2014 ◽  
Vol 119 (21) ◽  
pp. 12,391-12,419 ◽  
Author(s):  
M. Grygalashvyly ◽  
G. R. Sonnemann ◽  
F.-J. Lübken ◽  
P. Hartogh ◽  
U. Berger
Keyword(s):  
Hydroxyl Layer ◽  
Mean State

Energy changes in dehydration processes of clay minerals

Clay Minerals ◽  
1967 ◽  
Vol 7 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Toshio Sudo ◽  
Susumu Shimoda ◽  
Shigeru Nishigaki ◽  
Masaharu Aoki
Keyword(s):  
Clay Minerals ◽  
Adiabatic Calorimeter ◽  
Silicate Layer ◽  
Interlayer Region ◽  
Heat Of Transition ◽  
Dehydration Processes ◽  
Hydroxyl Layer

AbstractUsing the adiabatic calorimeter which has been developed by Nagasaki & Takagi (1948) and manufactured by the Rigaku Denki Company, the energy changes associated with the dehydration and dehydroxylation processes of clay minerals were measured at room pressure. The samples studied were mont-morillonite, chlorite (trioctahedral type), and three kinds of interstratified minerals with component layers such as mica, dioctahedral chlorite, and montmorillonite. ΔH-values due to the dehydration of the interlayer region were 9·8 kcal/H2O mole for montmorillonite and 12·4–13·4 kcal/H2O mole for interstratified minerals mica-montmoriIlonite and dioctahedral chlorite-montmorillonite. The values due to dehydroxylation of the silicate layer were 17·7 kcal/H2O mole for montmorillonite, 16·8–17·5 kcal/H2O mole for the interstratified mica- montmorillonite, and 19·3 kcal/H2O mole for chlorite. The value for the dehydroxylation of the hydroxyl layer of chlorite was 19·3 kcal/H2O mole. For the sake of comparison, the heat of transition α↔β of quartz was found to be 140 cal/mole. The reproducibility of these values was in the range of ±5%.

IR spectra of the hydroxyl layer of ?-A12O3

1979 ◽  
Vol 30 (5) ◽  
pp. 625-628 ◽  
Author(s):  
A. I. Trokhimets ◽  
P. P. Mardilovich ◽  
G. N. Lysenko
Keyword(s):  
Ir Spectra ◽  
Hydroxyl Layer
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