Stark deceleration of lithium hydride molecules

We describe the production of cold, slow-moving LiH molecules. The molecules are produced in the ground state using laser ablation and supersonic expansion, and 68% of the population is transferred to the rotationally excited state using narrowband radiation at the rotational frequency of 444GHz. The molecules are then decelerated from 420m/s to 53m/s using a 100 stage Stark decelerator. We demonstrate and compare two different deceleration modes, one where every stage is used for deceleration, and another where every third stage decelerates and the intervening stages are used to focus the molecules more effectively. We compare our experimental data to the results of simulations and find good agreement. These simulations include the velocity dependence of the detection efficiency and the probability of transitions between the weak-field seeking and strong-field seeking quantum states. Together, the experimental and simulated data provide information about the spatial extent of the source of molecules. We consider the prospects for future trapping and sympathetic cooling experiments.Comment: 14 pages, 6 figures; minor revisions following referee suggestion

Formation of Ultracold Heteronuclear Dimers in Electric Fields

The formation of ultracold molecules via stimulated emission followed by a radiative deexcitation cascade in the presence of a static electric field is investigated. By analyzing the corresponding cross sections, we demonstrate the possibility to populate the lowest rotational excitations via photoassociation. The modification of the radiative cascade due to the electric field leads to narrow rotational state distributions in the vibrational ground state. External fields might therefore represent an additional valuable tool towards the ultimate goal of quantum state preparation of molecules

Formation and interactions of cold and ultracold molecules: new challenges for interdisciplinary physics

Progress on researches in the field of molecules at cold and ultracold temperatures is reported in this review. It covers extensively the experimental methods to produce, detect and characterize cold and ultracold molecules including association of ultracold atoms, deceleration by external fields and kinematic cooling. Confinement of molecules in different kinds of traps is also discussed. The basic theoretical issues related to the knowledge of the molecular structure, the atom-molecule and molecule-molecule mutual interactions, and to their possible manipulation and control with external fields, are reviewed. A short discussion on the broad area of applications completes the review.Comment: to appear in Reports on Progress in Physic

Motivations for collaborating with industry: has public policy influenced new academics in Argentina?

Between 2005 and 2015 a series of science, technology and innovation policies were deployed in Argentina among which academic research collaborations with industry was particularly fostered. This paper studies the effect of those policies on newer researchers, defined as those with PhD or postdoctoral scholarships, looking at their motivations to collaborate and, to some extent, at their actual collaborations with Industry. Our hypothesis is that those policies had a positive effect on young academics’ perception of collaborations with industry, now conceived as a dimension of their job, and also on actual collaborations. To conduct our study, we used an original database constructed from an online survey answered by more than 600 newer researchers. Empirical results partly confirm our hypothesis: a direct policy encouraging collaborations by providing collaborative grants was not associated with actual collaborations, while orienting research towards strategic areas–defined by the Science and Technology Ministry- is

Investigación de las deficiencias nutritivas en un suelo de la zona pampeana mediante ensayos en macetas con alfalfa

Mediante un ensayo en macetas completamente aleatorizado, con cuatro repeticiones, realizado en invernáculo de la Facultad de Agronomía de la Universidad Nacional de La Pampa, se estudió la disponibilidad de macroelementos (Mg, Ca, S, K, P Y N) Y microelementos (Zn, B, Mn, Cu y Mo) en alfalfa. Se sembró 1,00 gramo de semilla de la variedad Painé INT A en macetas conteniendo 850 gramos de suelo homogeneizado, tamizado, proveniente del establecimiento "El Estribo" ubicado a 35 kilometros al sur de Santa Rosa, departamento Toay. El riego no fue limitante manteniéndose el suelo a capacidad de campo. Se agregaron por maceta los siguientes fertilizantes: KH2P04 1,00 gramo; CaSO4 0,40 gramos; MgC03 0,12 gramos; K2S04 1,00 gramo; Ca(OH)2 0,22 gramos; NH4H2P04 1,00 gramo y NH4N03 0,23 gramos en solución. Los microelementos se adicionaron en solución. Bajo las condiciones de humedad y temperatura controladas los resultados del ensayo indican que el suelo carece de disponibilidad de P y de S. Los micronutrientes estudiados no denotan deficiencias salvo el Mo que se presenta como el más limitante. Director: Ing. Agr. Nilda Reinaudi (cátedra de Química Analítica) Sub-director: Ing. Agr. Rosa M. de Troiani (cátedra de Fotoquímica

Formation of ultracold polar molecules via Raman excitation

Alkali hydride molecules are very polar, exhibiting large ground-state dipole moments. As ultracold sources of alkali atoms, as well as hydrogen, have been created in the laboratory, we explore theoretically the feasibility of forming such molecules from a mixture of the ultracold atomic gases, employing a two-photon stimulated radiative association process — Raman excitation. Using accurate molecular potential energy curves and dipole transition moments, we have calculated the rate coefficients for populating all the vibrational levels of the X$^1{\rm \Sigma}^+$ state of LiH via the excited A$^1{\rm \Sigma}^+$ state. We have found that significant molecule formation rates can be realized with laser intensities and atomic densities that are attainable experimentally. Because of the large X state dipole moment, rapid cascade occurs down the ladder of vibrational levels to v=0. The calculated recoil momentum imparted to the molecule is small, and thus negligible trap loss results from the cascade process. This allows for the build-up of a large population of v=0 trapped molecules

Modelos universitarios en pugna: democratización o mercantilización de la universidad y del conocimiento público en Argentina University models en pugna: democratization or mercantilizacion of the university and of public knowledge in Argentina

Los cambios ocurridos en el sistema universitario argentino se vinculan al modelo económico neoliberal que cobró fuerza en los 90. A partir de entonces, las universidades comenzaron a adecuar sus actividades a una nueva cultura de interacción con el sector productivo en busca de competitividad. En este escenario ubicamos dos discursos en disputa: uno enmarcado en las tendencias a democratizar los espacios públicos y el conocimiento libre; y otro vinculado a la tendencia de mercantilizar la educación y el conocimiento. Ambos tienen presencia en la universidad de hoy y su convivencia da lugar a posicionamientos fuertemente antagónicos que se corresponden con posiciones encontradas acerca de dos distintos modelos universitarios.<br>The changes that occurred in the Argentine university system are connected to the neoliberal economic model which was reinforced in the 90s. Since then, the universities adapted their activities to a new culture of interaction with the productive sector in search of competitiveness. In this context, we locate two speeches: one affirms the trend of democratizing public spaces and free knowledge; and the other, the trend to commercialize knowledge. Both circulate in the university today in strongly antagonistic positions that correspond with two different university models