Departamento de Física


Aula 23H. Dpto. Física-UNS. Viernes 26/10. 17:30hs.

Dr. Gábor Vári
Department of Applied
and Environmental Chemistry.
University of Szeged
Szeged, Hungary

Interaction of metals with the hexagonal boron nitride monolayer studied on Rh(111)
Two dimensional monolayers (MLs) of hexagonal boron nitride (h-BN) are promising insulator components for nanoelectronics. The h-BN monolayer has a similar structure and lattice constants as those of graphene. On Rh(111) surface, monolayer h-BN forms a periodically corrugated surface structure, called “nanomesh”. This phenomenon allows its application as a nanotemplate.
Here we report on the growth of gold and rhodium on the h-BN/Rh(111) surface and on subsequent thermal effects studied by STM, XPS and LEIS. The latter technique reveals the elementary composition of the outermost atomic layer. The h-BN monolayer was formed on Rh(111) by the decomposition of borazine (BAz) at high temperatures (1000 K). Gold forms 1-2 atomic layer thick nearly 2D nanoparticles, when it is evaporated in small amounts (~0.15 ML) on the nanomesh at 300 K. At higher coverages, the growth is strongly 3D. The gold peak was observed at a rather low position (83.7 eV), indicating significant electronic interaction either with h-BN. Indeed, previous density function theory (DFT) calculations indicated an electron transfer from boron nitride to gold. The intercalation of gold is the dominant process upon stepwise thermal annealing to 1050 K, but agglomeration and evaporation also occur to a limited extent. Interestingly, though gold and rhodium form a surface alloy after intercalation, the presence of ~0.15-0.50 ML of Au below the h-BN layer does not significantly influence the nanomesh structure. At higher gold doses a partial or full flattening of the nanomesh was observed. Surface alloying of gold and rhodium and the interaction of these metals with the h-BN layer are addressed with DFT calculations as well.
We also investigated the growth of h-BN on Au-Rh alloyed surfaces varying the gold content until 4 ML. In these measurements gold was evaporated on Rh(111) at 500 K, followed by annealing at 1000 K for 5 min. Subsequently, the surface was gradually exposed to BAz at 1000 K. The exposure was increased until the whole metal surface was covered by h-BN, as shown by LEIS, but not above 260 L. Decomposition of BAz on the alloyed surface led to the attenuation of both Rh and Au LEIS (normalized) intensities and Au signal slowed down with increasing Au content. It was shown by STM measurements that up to a gold coverage of 0.5 ML, the nanomesh structure is only slightly disturbed, but larger parts are flattened at higher Au doses. LEIS studies on the growth of rhodium on h-BN/Rh(111) indicated a predominantly 3D growth, similar to the gold case. When small amounts of rhodium (up to 1 ML) were deposited on h-BN/Rh(111), intercalation was nearly complete upon annealing to ~900 K, while dewetting of the h-BN layer set in at ~1050 K. At higher rhodium doses, complete intercalation could not be reached at any temperatures.


Aula 23H. Dpto. Física-UNS. Viernes 26/10. 16:30hs.

Dr. Laszlo Deák


Reaction Kinetics and Surface
Chemistry Research Group.
Szeged, Hungary

Activation of small molecules on oxides and oxide-metal interfaces
The catalytic activation of small molecules, like CO, H2O and H2 is of importance in different processes, such as hydrogenation of CO and water gas shift reaction, for which metal oxide supported rhodium catalysts are widely applied. The critical role of metal particle-oxide interface in activating small molecules was established under high pressure conditions , but have rarely been addressed by UHV model studies. We have studied the impact of rhodium-titania and Rh-molybdena interfaces on the CO and H2O decomposition by AES, ISS, STM, XPS, TPD and sensitive temperature-programmed work function (WF) measurements.
The TiOx overlayers were formed by annealing the TiO2(110) supported rhodium, while the atomically thin MoOx deposits by the oxidation of Mo. Both oxides exerted inhibition effect on the molecular bonding of CO, which, however, was accompanied by considerable promotion of CO dissociation, maximized at 0.2-0.3 ML oxide coverages. The MoOx overlayer, having much lower surface free energy than the atomically thin TiOx film, completely covered the Rh particles by annealing to 650 K and eliminated the CO adsorption capability of the surface. On the contrary, the titania supported Rh particles showed the maximum CO dissociation propensity after annealing to 700 K. The maximization of CO decomposition is straightforwardly associated with the active role of metal particle-oxide interfaces. Desorption peak temperature for the associative CO desorption on the MoOx modified Rh particles (Tp=700 K) suggests a lower activation energy in the recombination reaction of Oa and Ca atoms, than that for the TiOx covered surfaces (Tp=800 K) which allows higher reaction rates for these intermediates in the former case. Our UHV study is in harmony with the results of high pressure experiments, concerning the formation of carbon intermediate from CO dissociation during CO methanation.
The reactions of water showed variety with the extent of reduction of titania support. Strongly reduced surfaces produced H2O and H2 desorption states with Tp=370 and 470 K, corresponding to recombinative and dissociative reaction paths of the surface OH moieties. The interaction of water with the Rh-TiOx interface was characterized with a H2 desorption state at 580 K, arising from OH groups exhibiting maximal population at intermediate TiOx coverages. The concomitant operation of inhibition and promotional effects of metal oxide overlayers on the adsorption properties of a metal could be rationalized with a simple island model. Some extreme hydrogen dissolution properties of a strongly reduced, black titania crystal have also been revealed.


Sala de conferencias. Departamento de Ing. Eléctrica y de Computadoras.
Viernes 19/10. 16:00hs.

Dr. Juan Sebastián Ardenghi
Universidad Nacional del Sur

Diagramas de Feynman en Teoría Cuántica de Campos y materia condensada
Los diagramas de Feynman revolucionaron la forma de calcular secciones eficaces en Teoría Cuántica de Campos. Mediante estos diagramas fue posible organizar y visualizar la serie perturbativa de los procesos de la electrodinámica cuántica. Mediante un conjunto de reglas sencillas, que asignan factores algebraicos a cada elemento del diagrama, fue posible reinterpretar la física involucrada y poder hacer predicciones con alto grado de exactitud. En esta charla se contará como se construyen estos diagramas, que son las antipartículas, que son las partículas virtuales y como se aplican estas técnicas a la física del estado sólido.

Inicio: viernes 24 de agosto 16:30 hrs, Aula 121

Duración: 60 hrs.

Lugar: Aula 121, 1er piso cuerpo “B”

Días y Horarios: martes y viernes de 16:00 a 18:00

                                                                                                Profesor Responsable: Dr. Miguel D. Sánchez

                                                                                            Profesor Asociado DE, Departamento de Física (UNS)

                                                                                            Investigador Independiente, IFISUR (UNS-CONICET)


Inicio: viernes 24 de agosto 16:30 hrs, Aula 121

Duración: 60 hrs.

Lugar: Aula 121, 1er piso cuerpo “B”

Días y Horarios: martes y viernes de 16:00 a 18:00

                                                                                                Profesor Responsable: Dr. Miguel D. Sánchez

                                                                                            Profesor Asociado DE, Departamento de Física (UNS)

                                                                                            Investigador Independiente, IFISUR (UNS-CONICET)


 Noticias del Departamento
 6 Abr 2018

Cursos Remediales de FÍSICA


IMPORTANTE: Comienzo de clases  Lunes 16/04/18

               Distribución de comisiones por carrera







Ingeniería Civil

Ingeniería Mecánica

Ingeniería Industrial


Lunes 12 a 14 hs.

Miércoles 12 a 14 hs.


Aula 1 – 12 de Octubre y San Juan


Tecnicatura Universitaria en Óptica

Ingeniería Electrónica

Ingeniería Electricista

Profesorado en Física

Licenciatura en Física

Licenciatura en Geofísica

Lunes 8 a 10 hs.



Miércoles 8 a 10 hs.

 Aula 23H – Complejo Alem (Alem 1253)



Aula 116 (ex 80C) Av. Alem 1253



 Noticias del Departamento
 28 Dic 2017




DE 8:00 A 13:15 Y DE 14:00 A 14:30



DE 14:00 A 20:00


DE 14:00 A 18:00

 Noticias del Departamento
 12 Dic 2017
Curso de VERANO 2018


PERIODO DE INSCRIPCION: 12/12/17 AL 22/12/17

Asignatura: FISICA I- FISICA A

Prof: Dr. Walter REIMERS

AULA 6 Edificio 12 de Octubre - Horario: 8hs a 12hs

Inicio: 29 de enero de 2018


Prof. Dr. Oscar NAGEL

AULA 1 Edificio 12 de Octubre - Horario: 8hs a 12hs

Inicio: 29 de enero de 2018


commInteracción metal-Ceria y su actividad catalítica.
Una perspectiva teórica

Dra. M. Verónica Ganduglia-Pirovano
Instituto de Catálisis y Petroleoquímica-CSIC
Madrid, España

Ceria (CeO2) es uno de los más importantes óxidos de los elementos de tierras raras con usos en la catálisis industrial debido a sus condiciones de reducibilidad. La complejidad de los catalizadores en polvo reales dificulta en entendimiento básico de como es su comportamiento. Una forma de revelar este comportamiento es mediante la preparación de catalizadores modelo o modelos teóricos. En esta charla se presentaran resultados recientes de catalizadores modelo Ni, Co y Cu soportados sobre ceria como ejemplos de la catálisis del reformado en seco de metano (DRM: CH4+CO2 -> 2H2+2CO). Además, el sistema Ni/ceria se considerará para la producción de hidrógeno. El enfoque teórico se orienta a escribir a ceria como material soporte. La habilidad de ceria para estabilizar especies oxidadas (MOx: Co2+ y Ni2+) sobre superficies estequiométricas de CeO2 mediante una relocalización de estados f y estados metálicos (M0: Co0, Ni0) sobre el soporte reducido, CeO2-x, resulta esencial para la actividad catalítica en la reacción DRM.
La disociación de metano (CH4 -> CH3 -> CH2 -> CH -> C) ocurre a temperatura ambiente sobre MOx/CeO2, mientras que la disociación de CO2 ocurre sobre centros metálicos M0/CeO2-x en vacancias de oxígeno formadas a altas temperaturas (C + Osurf -> COgas + Vac). El sistema Co/ceria es el más activo con una barrera para la disociación de metano que se torna despreciable en la medida que la transformación MOx/CeO2 -> M0/CeO2-x se desarrolla con el incremento de la temperatura.

Jueves 09/11. 16hs.
Sala de conferencias
(Av. Alem 1253 - Cuerpo B - Subsuelo)

Departamento de Física, Universidad Nacional del Sur
 Avenida Alem 1253 - Bahía Blanca, Buenos Aires, Argentina
 Tel: 54-(0291)-4595141
 Fax: 54-(0291)-4595142
2010 - 2020
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