To realize supersonic combustion of hydrocarbons, an effective atomizer-igniter combination with the capabilities of fuel preheating, atomization, penetration, mixing, ignition and flameholding is desired. An original design concept incorporating these capabilities was built and tested at Virginia Tech, and was found to provide good penetration, effective atomization, and robust ignition and flameholding. Quiescent testing with kerosene and JP-7 provided initial performance data. The atomizer-injector design was then modified for insertion into a supersonic wind tunnel, and tested with kerosene in an unheated Mach 2.4 flow with typical freestream conditions of To = 280 K and Po = 360 kPa. Water injection was utilized in both cases for comparison and to analyze atomization behavior. In the quiescent environment, the regeneratively cooled plasma torch igniter was found to significantly increase electrode life while heating, atomizing, and igniting the liquid fuel. Jet breakup length was measured and characterized, and mean droplet size was estimated using an existing correlation. Several qualitative observations regarding quiescent combustion were made, including torch power effects and the process of flame formation. In the supersonic environment, the effect of fuel injection direction was analyzed. Best results were obtained when fuel was injected with a velocity component opposite to the direction of main tunnel flow. Repeatable ignition occurred in the supersonic boundary layer at the fuel stagnation location near the plasma torch plume. Direct, filtered, shadowgraph, and schlieren photographs, temperature measurements, and visible emission spectroscopy provided evidence of combustion and the details of the flame structure. The new atomizer-igniter design provided robust and reliable ignition and flameholding of liquid hydrocarbon fuels in an unheated supersonic flow at M=2.4, with no ramp, step, or other physical penetration into the flowpath. / Master of Science

<p> The Manitoulin Formation on Manitoulin Island consists of a lower biostrome extending across the island and an upper biohermal accumulation just south of Manitowaning. </p> <p> Viscible hydrocarbon accumulations occur in the bioherm, mostly contained in the more porous framework corals Paleofavosites and Palaeophyllum. Hydrocarbons found in other sample sites across the island show a very low bulk weight per cent and are of no economic significance. </p> <p> The bulk of the hydrocarbon was likely formed in lower carbonates near the centre of the Michigan Basin. Petroleum is also thought to have been introduced with solutions which formed calcite deposits. </p> / Thesis / Bachelor of Science (BSc)

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 122-136).

Thesis (M.S.) -- Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Master of Science / Department of Geology / Matthew Totten / Petroleum producing areas within the mid-continent region discovered in the first half of the 1900’s often ignored the potential of deeper horizons once hydrocarbons were discovered in shallower zones. In Ness County, Kansas the deepest horizon typically explored are Mississippian-aged rocks. One of the largest fields in Ness County is the Aldrich Field, first discovered in 1929. The Mississippian in this field contains an active water-drive, which was produced by an “open-hole” completion method. This precluded drilling deeper horizons. Although modern drilling and completion techniques allow drilling through and isolating water-drive reservoirs like the Mississippian, very few deep exploratory wells have been drilled in Ness County. Wells that penetrate sub-Mississippian horizons are typically drilled as disposal wells, along the flanks of the main structure. This study evaluates the potential of several sub-Mississippian formations to be hydrocarbon reservoirs. Drill cuttings from five wells that penetrate these formations were analyzed using a combination of petrographic microscope, Scanning Electron Microscope (SEM), and chemical methods. Reservoir quality porosity was observed in several sub-Mississippian zones. The presence of hydrocarbon staining was observed in the Viola samples of three wells, and the Arbuckle in one well. Staining was confirmed by EDS spectra under the SEM. The results of this study suggest a good potential of zones deeper than normally drilled to contain hydrocarbons in rocks with reservoir quality porosity. These zones were not drill stem tested in the Aldrich field, and structural advantage to these wells might be expected by drilling the apex of the trapping anticline to further evaluate the deeper horizons.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Bioconversion of hydrocarbons to value-added intermediates and products has significant industrial potential using both prokaryotic and eukaryotic organisms. In particular, alkanes can be converted to an expansive range of commercially important products using aerobic bioprocesses under mild process conditions. Coupled with the relative abundance of alkanes derived from gas to liquid (GTL) technologies, such as those employed by SASOL, South Africa, the commercial potential for bioconverison of alkanes is large. However, unlike carbohydrate substrates, alkane feedstocks are devoid of oxygen in their molecular structure. This means that the entire oxygen demand needs to be met by oxygen transfer. Furthermore, a decline in oxygen transfer in aqueous-hydrocarbon dispersions with increasing alkane concentration has been observed to result from depression of the overall volumetric oxygen transfer coefficient (KLa). Therefore, understanding KLa and the fundamental parameters underpinning its behaviour is critical to ensuring the bioprocess is kinetically, rather than transport, limited in terms of both operation and scale-up. Previous studies have examined KLa in aerated-alkane-aqueous systems. In light of the importance of oxygen transfer in bioprocesses, this study expands on the KLa understanding in 3-phase studies by including a fourth solid phase, thus more closely representing a hydrocarbonbased bioprocess. The project aimed to determine the impact of agitation, alkane concentration and solid loading on the Sauter mean bubble diameter (DSM), gas hold-up and specific interfacial area (a) and correlate these parameters to KLa. This ultimately determined which parameter was dominant over a range of process conditions. Furthermore, concurrent measurement of the KLa and interfacial area meant the behaviour of the liquid side oxygen transfer coefficient (KL) could be defined, providing further insight into how changes in the process conditions impact on KLa. Experiments were conducted in a 5 litre stirred tank bioreactor containing n-C14-20 straight chain alkane, sparged with air at 0.8 vvm. In line with process conditions typical of a hydrocarbonbased bioprocess, KLa and a were measured for agitation rates from 450 to 1000 RPM, alkane concentrations from 2 to 20% v/v and yeast solids from 1 to 10 g/l. KLa was measured using the gassing out procedure using a dissolved oxygen (DO) probe which measured the response of the system to a step change in the sparge gas oxygen pressure. The probe response lag ( P), equal to the time taken for the probe to reach 63.2% of the saturation DO concentration, was determined for every set of process conditions. The inverse of P, KP was taken into account when calculating KLa from the DO probe response. The area was calculated from DSM and gas hold-up. DSM was quantified using high speed photography and image analysis was performed in Matlab® using bespoke routines. Elimination of optical distortion and the development of an adequate light source was key to acquiring clear images. Both KLa and interfacial area were found to be affected by changes in agitation, alkane concentration and yeast loading. An increase in agitation increased the KLa over the entire range of alkane concentration and yeast loading. Similarly, an increase in agitation resulted in an increase in interfacial area, underpinned by a decrease in the DSM. It is therefore likely that the interfacial area plays a dominant role in defining KLa when considering an increase in agitation. Increases in alkane concentration resulted in a peak in KLa between 2.5 and 5% alkane concentration while further increases in alkane concentration depressed KLa. This peak was not observed in interfacial area, where an increase in alkane concentration resulted only in a decrease in interfacial area, thus indicating a positive influence of KL on KLa at low alkane concentrations. Further increases in alkane concentration beyond those creating the peak KLa resulted in KLa depression, suggesting that the increasing viscosity imparted by the alkane decreases both KL and interfacial area. Increased yeast loading had opposing effects at low and high agitation rates. At low agitation rates, increased loadings were observed to increase KLa, while increased loadings at high agitation rates caused a decrease in KLa. This behaviour was also evident in interfacial area, suggesting that in this regime KLa was defined by interfacial area behaviour. Increased yeast loading was observed to depress the KLa for all alkane concentrations when examined at a constant midpoint agitation rate. This trend was not evident in interfacial area, which increased with increasing yeast loading at the same agitation rate. The positive influence of yeast on interfacial area was likely caused by adhesion of the yeast particles to the bubble surface, lowering the DSM by preventing coalescence. The disagreement between the KLa and interfacial area results suggested that yeast loading impacted negatively on KL, which had an over-riding negative impact on KLa. The use of reliable methods for the determination of both interfacial area and KLa were demonstrated for application in model hydrocarbon-based bioprocesses. The combined results offer a unique insight into how changes in the process conditions impact independently on KL and interfacial area, which when combined ultimately defined the KLa behaviour. Quantification of the relative magnitude of the impact each parameter had on KLa contributed toward a fundamental understanding of oxygen transfer in model hydrocarbon-based bioprocesses. / AFRIKAANSE OPSOMMING: Biologiese omsetting van koolwaterstowwe na produkte met finansiële waarde het beduidende industriële potensiaal met behulp van beide prokariotiese en eukariotiese organismes. In die besonder, kan alkane omgeskakel word na ’n uitgebreide reeks van kommersieel belangrike produkte met behulp van aerobiese bioprosesse onder ligte proses voorwaardes. Tesame met die relatiewe oorvloed van alkane afgelei van GTL tegnologie, soos dié van Sasol, Suid-Afrika, die kommersiële potensiaal vir bioconverison van alkane is groot. Maar, in teenstelling koolhidrate substrate, alkaan voerstowwe is beroof van suurstof in hul molekulêre struktuur. Dit beteken dat die hele suurstof vereiste moet nagekom word deur suurstof oordrag. Verder het ’n afname in suurstof oordrag in waterige-koolwaterstof dispersies met toenemende alkaan konsentrasie waargeneem te lei van depressie van die algehele volumetriese suurstofoordragkoëffisiënt (KLa). Daarom verstaan KLa en die fundamentele parameters onderliggend sy gedrag is van kritieke belang om te verseker dat die bioprocess is kineties, eerder as vervoer, beperk in terme van beide werking en skaal-up van bioprosesse. Vorige studies het KLa in deurlug-alkaan-waterige stelsels ondersoek. In die lig van die belangrikheid van suurstof oordrag in bioprosesse hierdie studie brei uit op die KLa begrip in driefase studies deur die insluiting van ’n vierde soliede fase, dus meer nou wat ’n koolwaterstofgebaseerde bioprocess. Die doel van die projek is om die impak van vermengingstempo, alkaan konsentrasie en soliede inhout op die Sauter gemiddelde borrel deursnee (DSM), gas-vasvanging en spesifieke gas-vloistof oppervlakarea (a) te kwantifiseer en korreleer met KLa gedrag. Dit sou defineer die dominante parameter oor ’n verskeidenheid van proses voorwaardes. Verder, gelyktydige meting van die KLa en oppervlakarea kan die gedrag van die vloeistof-kant suurstofoordragkoëffisiënt (KL) gedefinieer. Dit sal verskaf verdere insig in hoe die veranderinge in die proses voorwaardes impak op KLa. Eksperimente was uitgevoer in ’n 5 liter belugte geroerde tenk bioreaktor bevat n - C14-20 reguitketting alkane, met lug met lug deurgeborrel by 0.8 VVM. In lyn met die proses voorwaardes tipies van ’n koolwaterstof-gebaseerde bioprocess, KLa en a was gemeet vir vermengignstempos van 450-1000 RPM, alkaan konsentrasies van 2-20 % v/v en gis vastestowwe van 1 tot 10 g / l. KLa is gemeet deur die vergassinguit prosedure met behulp van ’n suurstofmeter wat die reaksie van die stelsel na ’n stap verandering in die voer gas suurstof druk gemeet het. Die suurstofmeter reaksie vertraging ( P), gelyk aan die tyd wat dit neem vir die suurstofmeter 63.2 % van die versadiging DO konsentrasie te bereik, is bepaal vir elke procesopset. Die inverse van P, KP is in ag geneem by die berekening van KLa uit die suurstofmeter reaksie. Die gas-vloistof oppervlak is bereken vanaf DSM en gas hold-up. DSM is gekwantifiseer met behulp van hoë spoed fotografie en beeld analise is uitgevoer in Matlab ® roetines. Uitskakeling van optiese vervorming en die ontwikkeling van ’n voldoende ligbron was die sleutel tot die verkryging van helder beelde. Beide KLa en grens oppervlakarea gevind geraak word deur veranderinge in vermengignstempo, alkaan konsentrasie en gis laai. ’N toename in geroer het die KLa verbeter oor die hele reeks van alkaan konsentrasie en gis laai. Net so, ’n toename in geroer het gelei tot ’n toename in grens oppervlak, ondersteun deur ’n afname in die DSM. Dit is dus waarskynlik dat die grens oppervlak speel ’n dominante rol in die definisie van KLa by die oorweging van ’n toename in roering. Stygings in alkaan konsentrasie gelei tot ’n hoogtepunt in KLa tussen 2.5 en 5 % alkaan konsentrasie terwyl verdere verhogings in alkaan konsentrasie druk die KLa af. Die piek was nie in oppervlakarea duidelik, waar ’n toename in alkaan konsentrasie gelei net tot ’n afname in oppervlakarea, dus dui op ’n positiewe invloed van KL op KLa teen lae alkaan konsentrasies waargeneem. Verdere stygings in alkaan konsentrasie verder as die skep van die piek KLa gelei tot KLa depressie, wat daarop dui dat die toenemende viskositeit meegedeel deur die alkaan verminder beide KL en grens oppervlak. Verhoogde gis laai het opponerende effekte teen ’n lae en hoë vermengingstempo. By lae vermengingstempo, ’n verhoging in gis laai waargeneem KLa te verhoog, terwyl ’n verhoging in gis laai op ’n hoë vermengingstempo veroorsaak ’n afname in KLa . Hierdie gedrag was ook duidelik in grens oppervlak, wat daarop dui dat daar in hierdie regime KLa gedefinieer deur grens oppervlak gedrag. Verhoogde gis laai waargeneem die KLa te onderdruk vir alle alkaan konsentrasies wanneer ondersoek teen ’n konstante middelpunt vermengingstempo. Hierdie tendens was nie duidelik in tussenvlak gebied, wat verhoog met toenemende gis laai op dieselfde geroer koers. Die positiewe invloed van gis op grens oppervlak is waarskynlik veroorsaak deur adhesie van die gis deeltjies aan die borrel oppervlak, die verlaging van die DSM deur die voorkoming van die saamsmelting van gasborrels. Die meningsverskil tussen die KLa en grens oppervlakarea resultate voorgestel dat gis laai negatiewe uitwerking op KL, met ’n dominante negatiewe impak op KLa. Die gebruik van ’n betroubare metodes vir die bepaling van beide oppervlakarea en KLa gedemonstreer vir toepassing in model koolwaterstof-gebaseerde bioprosesse. Die gekombineerde resultate bied ’n unieke insig in hoe die veranderinge in die proses voorwaardes impak onafhanklik op KL en oppervlakarea, wat wanneer gekombineer gedefinieer die KLa gedrag. Kwantifisering van die relatiewe grootte van die impak elke parameter het op KLa bygedra tot ’n fundamentele begrip van suurstof oordrag in model koolwaterstof-gebaseerde bioprosesse.

No description available.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Cuticular hydrocarbon (CHC) profiles of insects play roles in behavioural interactions within and between species, encompassing species-, colony- and mate-recognition. CHCs are largely genetically determined and are thus unique to each species, making them useful in chemotaxonomy. However, species exhibit intra-species variation in their CHC profile which can be the result of both intra-species genetic variation as well as environmental influences such as habitat effects, colony effects, diet, host switching, as well as adsorption of CHCs from other insects. Studies have found that the CHC profiles of a specific insect species will often exhibit variations between regions as well as the species of host the insect is associated with. Therefore, an ideal system to investigate the effects of genetic population structure and environment on the CHC profiles of insects is within the fig – fig wasp mutualism. Fig species occur in a wide variety of habitats and host a diverse complement of fig wasp species. We were therefore offered the opportunity to investigate a wide range of potential influences on fig wasp CHC profiles ranging from environmental to genetic effects. Firstly, through GC-MS we found that the CHC profiles of the fig wasps investigated are both species-specific and species-group-specific, with the species Elisabethiella glumosae, Elisabethiella stuckenbergi and Ceratosolen capensis, and two Otitesella species-groups (the Uluzi and Sesqui species-groups) separating out significantly. Consensus phylogenies (based on COI, Cytb and EF-1α) showed that within the galling fig wasp genus Otitesella there were multiple genetic lineages within a species-group which corresponds to species-level genetic variation, and that each genetic lineage was confined to a single host fig species. The CHC profiles reflected the genetic relationships between the two species-groups, and the CHC profiles within a species group could be differentiated by genetic lineage/host species. This indicated that although genetic lineage was mostly responsible for the observed variation in CHC profiles, factors associated with different host species also had an effect. Strong regional variation overriding both the influence of genetic lineage and factors associated with host species were observed in the CHC profiles of the fig wasps within a species-group. This regional variation in CHC profiles was also observed within two pollinating fig wasp species, Elisabethiella stuckenbergi and Ceratosolen capensis, which was not supported by population genetic data (COI and Cytb). In fact, very little genetic population structure was found within the pollinating species, even though the pollinators were collected across South Africa. The lack of genetic structure in pollinating fig wasps can be the result of high gene flow caused by the large dispersal capability of pollinating fig wasps. Our results indicated that fig wasp CHC profiles have the potential to be used in chemotaxonomy and are possibly used as species and mate-recognition cues by the fig wasps. Furthermore, we found both a regional and associated host species effect on the CHC profile. We suggest that the observed regional effect in this study could be attributed to habitat differences and differences in fig wasp community between regions. Moreover, the effect host species had on the CHC profiles may be as a result of dietary differences between galls in different host species. A possible consequence of the observed regional/host speciesassociated effect on fig wasp CHC profiles is that it could lead to pre-mating isolation within fig wasp species, which could ultimately result in speciation. In addition, our results indicated that the interpretation of the variation in the fig wasp CHC profile was dependent on the scale of the analysis: on a broad, inter-species-level scale, fig wasp CHC profiles were species-specific; on a finer intra-species scale, variation in CHC profiles occurred between fig wasps collected from different regions; and on a within-region scale, variation in CHC profiles within species-groups occurred between genetic lineages/host species. Future studies should look at the application of CHCs in chemotaxonomic studies on the fig wasp phylogeny, as well as the effect of fig wasp community composition on fig wasp CHCs. / AFRIKAANSE OPSOMMING: Kutikulêre koolwaterstof (KK) profiele van insekte speel rolle in die gedragsinteraksies binne sowel as tussen spesies, en behels die herkenning van spesieof kolonielidmaatskap asook potensiële maats. Kutikulêre koolwaterstowwe word meestal deur gene bepaal en is dus uniek vir elke spesie, wat dit handig maak vir chemotaksonomie. Spesies vertoon egter soms intraspesie variasie in hul KK profiele wat die gevolg kan wees van beide intraspesie genetiese variasie sowel as omgewingsinvloede soos habitat effekte, kolonie effekte, dieet, tussen-gasheer skuiwings, asook die adsorpsie van ander insekte se kutikulêre koolwaterstowwe. Studies het gevind dat die kutikulêre koolwaterstof profiele van ʼn spesifieke insek spesie op ʼn gereelde basis verskille vertoon tussen streke asook tussen die verskillende gasheer spesies waarmee die insek geassosieer is. Om hierdie redes is die vy – vy-wesp mutualisme ʼn ideale sisteem om die uitwerking van genetiese populasie struktuur en omgewing op die KK profiele van insekte te ondersoek. Vy spesies kom in ʼn wye verskeidenheid van habitatte voor en ondersteun ʼn diverse groep vy-wesp spesies. Dit het ons die geleentheid gebied om ʼn wye reeks moontlike invloede van vy-wesp KK profiele te ondersoek, van omgewings- tot genetiese invloede. Eerstens, deur die gebruik van GC-MS het ons gevind dat die KK profiele van die vy-wespe wat ondersoek was beide spesie-spesifiek en spesie-groep-spesifiek is, met die spesies Elisabethiella glumosae, Elisabethiella stuckenbergi en Ceratosolen capensis, asook twee Otitesella spesie-groepe (die Uluzi en Sesqui spesie-groepe) wat betekenisvol onderskei kon word. Konsensus filogenieë (gegrond op COI, Cytb en EF1-1α) het getoon dat daar in die gal-induserende vy-wesp genus Otitesella veelvuldige genetiese lyne binne die spesie-groepe voorgekom het ooreenstemmend met tussen-spesie genetiese variasie, en dat elke genetiese lyn beperk was tot ʼn enkele gasheer vy spesie. Die KK profiele het die genetiese verhoudings tussen die twee spesie-groepe weerspieël, en die KK profiele binne ʼn spesie-groep kon onderskei word op grond van hul genetiese lyn/gasheer spesie. Hierdie het getoon dat, alhoewel genetiese lyn meestal verantwoordelik was vir die waargeneemde variasie in KK profiele, faktore wat met verskille in gasheer spesies gepaard gaan ook ʼn effek gehad het. Sterk streeks-verbonde variasie wat beide die invloed van genetiese lyn, én faktore wat met verskille in gasheer spesie gepaard gaan, oortref het, was waargeneem in die KK profiele van die vy-wespe binne ʼn spesie-groep. Hierdie streeks-verbonde variasie in KK profiele was ook waargeneem in twee bestuiwende vy-wespe, Elisabethiella stuckenbergi en Ceratosolen capensis, ʼn resultaat wat nie ondersteun was deur die genetiese bevolkingsdata nie (COI en Cytb). In werklikheid was baie min genetiese bevolkings-struktuur opgespoor binne die bestuiwer spesies, selfs as was die bestuiwer spesies regoor Suid-Afrika ingesamel. Die tekort aan genetiese struktuur in die vy-wesp bestuiwers kan die gevolg wees van hoë geenvloei wat veroorsaak word deur die hoë verspreidingskapasiteit van bestuiwende vy-wespe. Die resultate toon aan dat vy-wesp KK profiele die potensiaal besit om in chemotaksonomie gebruik te word, en word moontlik deur vy-wespe gebruik as kenmerke vir die herkenning van spesie en potensiële maats. Verder was daar gevind dat daar beide ʼn streekseffek en ʼn effek geassosieer met gasheer spesie op KK profiele was. Ons stel voor dat die waargeneemde streekseffek in hierdie studie toegeskryf kan word aan verskille tussen habitatte asook streeksverbonde verskille tussen vy-wesp gemeenskappe. Boonop kan die effek wat gasheer spesie op die KK profiele gehad het ʼn gevolg wees van dieetverskille tussen die galle in verskillende gasheer spesies. ʼn Moontlike gevolg van die waargeneemde streeks/gasheer-spesie-geassosieerde effek op vy-wesp KK profiele is dat dit moontlik kon lei tot voor-paring-isolasie binne vy-wesp spesies, wat uiteindelik spesiasie kon veroorsaak het. Daarbenewens wys ons resultate dat die interpretasie van die variasie in die vy-wesp KK profiel was afhanklik van die skaal van die analise: op ʼn breë interspesie vlak was die vy-wesp KK profiele spesiespesifiek; op ʼn fyner intra-spesie vlak het variasie in KK profiele voorgekom tussen vy-wespe wat in verskillende streke ingesamel was; en op streeksvlak het variasie in die KK profiele binne spesie-groepe voorgekom tussen genetiese lyne/gasheer spesies. Toekomstige studies behoort te kyk na die toepassing van kutikulêre koolwaterstowwe in chemotaksonomiese studies van die vy-wesp filogenie, asook die effek wat vy-wesp gemeenskap samestelling het op vy-wesp kutikulêre koolwaterstowwe.

<p>Using x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) in combination with density functional theory (DFT) the changes in electronic and geometric structure of hydrocarbons upon adsorption are determined. The chemical bonding is analyzed and the results provide new insights in the mechanisms responsible for dehydrogenation in heterogeneous catalysis.</p><p>In the case of alkanes, <i>n</i>-octane and methane are studied. XAS and XES show significant changes in the electronic structure upon adsorption. XES shows new adsorption induced occupied states and XAS shows quenching of CH*/Rydberg states in <i>n</i>-octane. In methane the symmetry forbidden gas phase lowest unoccupied molecular orbital becomes allowed due to broken symmetry. New adsorption induced unoccupied features with mainly metal character appear just above the Fermi level in XA spectra of both adsorbed methane and <i>n</i>-octane. These changes are not observed in DFT total energy geometry optimizations. Comparison between experimental and computed spectra for different adsorbate geometries reveals that the molecular structures are significantly changed in both molecules. The C-C bonds in <i>n</i>-octane are shortened upon adsorption and the C-H bonds are elongated in both <i>n</i>-octane and methane.</p><p>In addition ethylene and acetylene are studied as model systems for unsaturated hydrocarbons. The validity of both the Dewar-Chatt-Duncanson chemisorption model and the alternative spin-uncoupling picture is confirmed, as well as C-C bond elongation and upward bending of the C-H bonds.</p><p>The bonding of ethylene to Cu(110) and Ni(110) are compared and the results show that the main difference is the amount of back-donation into the molecular π* orbital, which allows the molecule to desorb molecularly from the Cu(110) surface, whereas it is dehydrogenated upon heating on the Ni(110) surface. </p><p>Acetylene is found to adsorb in two different adsorption sites on the Cu(110) surface at liquid nitrogen temperature. Upon heating the molecules move into one of these sites due to attractive adsorbate-adsorbate interaction and only one adsorbed species is present at room temperature, at which point the molecules start reacting to form benzene. The bonding of the two species is very similar in both sites and the carbon atoms are rehybridized essentially to sp².</p>

No description available.