Pysics

We present a study to comprehend if the support given by higher education institution (HEI) to international students coming from the Portuguese-Speaking African Countries meets their academic and social hindrances. Our starting point was a set of semi-structured interviews focused on the perspectives of these students, their Professors and Course Directors as well as on the perspectives of HEI' staff. Despite findings indicate a positive institutional support, it seems there is still much to do in order to do it properly with these students. These different perspectives will allow us to reflect on the impact that those actions/resources have on the path of students from Portuguese-Speaking African Countries and to systematize suggestions to enhance their experiences in HE.

ABSTRACT In natural Si-rich brown diamonds a luminescence centre with a zero-phonon line at 2.818 eV and a room temperature decay time of 1.7 ms is often found. The vibronic coupling and the decay characteristics of the band are analysed. The luminescence originates mainly in two sublevels of a triplet electronic state that decays to a singlet ground state. The third triplet sublevel reaches thermal equilibrium with the other two above 40 K. The possibility of stimulated tunable emission from this centre is discussed.

Abstract The vibronic analysis of centres with zero phonon lines at 2.082 and 2.052 eV in natural brown diamonds is presented. Time-resolved spectra and its temperature dependence reveal a thermal population of higher energy emitting levels with a much ...

... Journal of Luminescence 38 (1987) 181183 NorthHolland, Amsterdam LONG LIVED RED LUMINESCENCE IN DIAMOND Estela PEREIRA and LucIlia SANTOS Departarnento e Centro ... INIC and JNICT for financial support and Mr. JM Januario for his help with the experiments. ...

ABSTRACT Luminescence emission bands originating in colour centres produced in natural topaz have been detected. These bands are studied by steady-state and time-resolved photoluminescence spectroscopy. We found that the energy of the emitting bands are different in colourless samples and in samples submitted to treatment and depend on the treatment itself. Also, there is an emission present in long-lived detection regimes, indicating the possible presence of non-radiative processes. These results are analysed and a possible correlation between structural and colour changes resulting from the irradiation and annealing treatment is addressed.

Abstract The vibronic structure and decay processes of centres occuring in brown diamonds with zerophonon lines at 2.974, 2.818 and 2.490 eV are analyzed. All have decay times in the μs-ms region, the decay processes being intrinsic to the centres, as they are sample ...

ABSTRACT The characteristics of an emission band observed in the photoluminescence in some natural and synthetic diamonds are analysed. Although its zero-phonon lines are very close in energy to the N3 centre zero-phonon line, this emission can be well identified due to its different lifetime and luminescence excitation spectrum. The nature of the centre is discussed.

ABSTRACT Export Date: 4 July 2012, Source: Scopus, CODEN: REDSE, doi: 10.1080/10420150215824, Language of Original Document: English, Correspondence Address: Santos, L.; Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal; email: lucilia@fis.ma.pt, References: Koidl, P., (1977) Phys. Rev. B, 15, p. 2493;

Preparation and characterization either by optical absorption, photoluminescence and micro-Raman spectroscopy of individual components as well as bilayers consisting of organic dye semiconductor Zinc Phthalocyanine (ZnPc) and fullerene, C60, thin films are reported. The layers and structures were deposited in vacuum and some fullerene films were also prepared by casting the C60 solution in benzene. The optical absorption and photoluminescence dependencies on film thickness in bilayers C60/ZnPc were observed and may be discussed in a context of interface induced simmetry reduction of C60 molecules.

ABSTRACTTime resolved photoluminescence and optically detected magnetic resonance experiments were performed on the 2.985 eV (N3) luminescence band in natural diamond and the 2.964 eV luminescence center in synthetic diamonds. For the N3 luminescence the resonance occurs in the 2E excited state of the center. On the 2.964 eV luminescence a strongly anisotropie resonance signal is observed. The frequency response of the magnetic resonance signals confirms the time resolved photoluminescence measurements.

OBJECTIVOS Urge reformular todo um percurso de práticas pedagógicas que se identificam com algumas «deformaçõ-es» (Perez, Montoro, Alis, Cachapuz, Praia, 2001) no que respeita ao ensino das ciências, na esperança de mudar atitudes e orientando-as para melhorar o processo de aprendizagem dos alunos. E é muito impor-tante verificar a efectividade dessas aprendizagens. Os Centros de Ciência, instituições de ensino não-formal, de objectivos predominantemente educativos e procura de público diferenciado, criam "oportunidades de aprendizagem em moldes bastante distintos dos do ensino formal, tanto no que respeita à vivência que é oferecida, como às temáticas abordadas ou ao grau de sistematização dos conhecimentos que é exigido." (Martins, 2000). Este estudo propõe-se confirmar a importância dos Centros de Ciência na promoção da aprendizagem das ciências e aumento da literacia científica dos alunos no 1º Ciclo do Ensino Básico, 1ºCEB, e o modo como se confirma essa aprendizagem.

ABSTRACT The Bologna Process, recently implemented in Portugal, has brought many changes to higher education institutions. One of these changes refers to a law that enables mature students (23 years and older) to gain special access to higher education, taking into account their professional experience and other biographical elements. The numbers of non-traditional students are therefore increasing in our country, making our academic population more diverse. We designed a research project to investigate the special circumstances of non-traditional students in our institutions, and to provide recommendations that should improve their academic lives. In this article, we describe survey results, focus-group interviews and life histories and use them to understand the transition of mature students into higher education. Our results include interpretations of the factors that students view as barriers to their participation in higher education, the importance of peer support, and reflections on life histories that provide greater insight into the transitional process. Although several barriers were identified by mature students, there is also a positive impact from transition. It is clear that transition today is no longer punctual or linear either in time or space. We should therefore challenge traditional views of the transition concept, in which students are considered a problem to higher education institutions, because this diverts attention away from the responsibilities of those institutions towards change.