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The dependence of the emission band is determined in terms of its intensity, width and lifetime on the Tm and erbium (Er) concentration and distribution in order to optimize efficiency and understand the energy transfer mechanisms between [Tm.sup.3+] and [Er.sup.3+]. The results have shown that enhanced performance with a flat broadband emission useful for planar integrated devices can be achieved by further dopant engineering in the nanoscale.

Landraces and bean (Phaseolus vulgaris L.) cultivars grown in Mexico are diverse, as are consumer preferences and agroecological production environments. Mexican common bean cultivars were analyzed using amplified fragment length polymorphism (AFLP) fingerprinting to examine the genetic relationships within and among races, based on the genotyping of 112 bred cultivars developed in Mexico. Molecular analysis of dry bean germplasm will be useful to corroborate previous cuitivar characterizations and establish the genetic basis of improved germplasm, to facilitate the use of that diversity, and to implement the use of markers in selection. Germplasm included 111 cultivars belonging to Mesoamerica (25), Jalisco (39), Durango (28), and Nueva Granada (19) races, which are commonly cultivated throughout the bean-producing areas of Mexico. A Mexican P. coccineus species cullivar (Blanco Tlaxcala) was also included for comparison. Broad genetic diversity was found within bean races, and diversity values between races were similar. Most of the Nueva Granada germplasm was clearly different from that of all other races, whereas the P. coccineus cultivar was distinct from all P. vulgaris cultivars. A dendrogram based on the AFLP analysis did not clearly match with that made on the basis of racial classification. This mismatch was probably due to genetic recombination between Andean (Nueva Granada) and Mesoamerican (Jalisco, Durango, and Mesoamerica) gene pools. Utilization of contrasting parents for specific crosses has also contributed to broadening the genetic basis of common bean., COMMON BEAN is a globally important crop that originated in the Americas. In Mexico, common bean breeding started in 1943, when native germplasm was first collected. The first bred cultivars [...]

Research describing a method of shape determination for nanocrystals in composite materials is presented. In particular the use of optical extinction spectroscopy with polarized light is shown to have applications in this field.

The role of size effects on the crystallization of amorphous Ge (a-Ge) in contact with Bi nanocrystals (NCs) is studied using in situ transmission electron microscopy annealing and the Avrami equation. Results show that a-Ge crystallization temperature decreases with increasing Bi metal contract area. The crystal growth of thin Ge layers also occurs through a zig-zag mechanism from one Bi NC to the next.

The excitation, optical activation and concentration limits of erbium in crystal silicon (Si) reveal that Er is excited by photocarrier-mediated processes. The luminescence intensity is increased by the rapid thermal annealing of Er at a temperature of 1,000 degrees Celsius in 15 seconds. The luminescence intensity increase is caused by an enhancement in the minority carrier lifetime in Er structures.

Nanosecond laser pulses were used to analyze crystallization and relaxation kinetics of amorphous germanium films on silicon. The thermal conductivity of the silicon substrate efficiently extracted the film-absorbed laser energy to facilitate amorphous regrowth of the films when subjected to melting and sudden solidifications.

Er-implanted oxygen-doped molecular beam epitaxial silicon films reveal a room temperature luminescence at about 1.54 micrometers. The maximum luminescence intensity occurs after annealing in the 700 to 800 degrees Celsius range. Higher-temperature annealing causes out-diffusion, oxygen evaporation and decrease in luminescence intensity.

Optical properties of amorphous semiconductor films are usually strongly dependent on deposition conditions. To the best of our knowledge, this is the first publication on optical properties of amorphous Ge films that are grown by laser-assisted deposition and measured by means of spectroscopic ellipsometry over a wide spectral range (1.43-4.59 eV). Optical properties of dc magnetron-sputtered and e-beam-deposited films are also included. Effective medium modeling is used to analyze the void fraction and the film homogeneity through the thickness. The results show that laser-deposited films and dc magnetron-sputtered films are similar, both being denser, more homogenous, and more stable than e-beam-deposited films. Transmission electron microscopy analysis shows that the results of the optical study are correlated to the film structure. These results are discussed in terms of the kinetic energy of the species involved in each deposition technique and some conclusions related to the laser-assisted deposition process are reported.

Pulsed laser deposition was utilized to develop active rare-earth Er-Yb co-doped phosphate glass films in a single step. When these films are deposited in low oxygen pressure, the highest refractive index, optical density and photoluminescence intensity and lifetime are achieved. Cross-relaxation of the Yb or the optical pumping of the Er ions can result to the excitation of luminescent emission.

The utilization of real time reflectivity measurements at the HeNe laser wavlength in the characterization of solid-liquid transition induced in antimony at 193 nm by pulsed laser irradiation is discussed. Reflectivity transients at energy densities above the melting threshold were analyzed. It was found that the melting for energy densities below 150 mJ cm-2 proceeds inhomogenously.

The variable angle spectroscopic ellipsometry technique is employed to determine the dielectric functions and optical constants of the different [Cu.sub.2]ZnGe[S.sub.4] bulk crystals grown by the Bridgman method. An increase in the Ge-S hybridization in the system is shown to lead to a significant reduction in the first gap.

The analysis has shown the efficient energy transfer from Si nanoparticles (NPs) to [Er.sup.3+] ions in a nonsilica-based material [Al.sub.2][O.sub.3]. The results have shown that a higher percentage of [Er.sup.3+] ions are sensitized by Si NPs and have stressed the importance of controlling the dopant distribution at the nanoscale to achieve improved device performance.

The analysis of the optical properties of bulk Cu[([In.sub.1-x][Ga.sub.x]).sub.3][Se.sub.5] mixed crystals prepared from the elements as a function of the Ga content is described. The values of the interband transitions are shown to increase linearly with the increasing Ga content.

A spectroscopic ellipsometry was used to determine the complex dielectric functions of Cu[In.sub.3][Se.sub.5] and Cu[In.sub.5][Se.sub.8] crystals with different Cu contents in the 0.8-4.7 eV photon energy range. The results obtained for the Cu-poor Cu[In.sub.3][Se.sub.5] and Cu[In.sub.5][Se.sub.8] samples which showed an increase in the band gap value could be used to design solar cells.

The optical constants of Cu[Ga.sub.5][Se.sub.8] crystals are modeled with different deviation from stoichiometry. The optical functions are analyzed in order to clarify the optical properties of nearly stoichiometric and Cu-poor Cu[Ga.sub.5][Se.sub.8] crystals.

The modeling of the optical constants of [Cu.sub.2][In.sub.4][Se.sub.7] and Cu[Ga.sub.3][Se.sub.5] is described. The results have provided a valuable set of data for [Cu.sub.2][In.sub.4][Se.sub.7] and Cu[Ga.sub.3][Se.sub.5] that can be useful for the design of solar cells based on these compounds.

A spectroscopic ellipsometry in the energy range from 0.5 to 4.7 eV at room temperature is used to determine the dielectric function epsi(omega) of polycrystalline bulk samples of the quaternary chalcopyrite semiconductors Ag(sub 1-x)Cu(sub x)InSe(sub 2) alloys. The results show that the value of the main energy gap is very sensitive to the composition and varies from 1.225 to 1.009 eV as x increases (Cu content).

The solidification dynamics of Sb films under different heat flow conditions, which are modified by varying the film thickness and the pulse duration, and fluence is investigated. The comparison of the behavior of these films with the case of Sb-rich GeSb ones makes it clear that relatively minor changes in the film composition can lead to big changes in the solidification dynamics under similar heat flow conditions that are beneficial for the application of such films in phase change optical recording with ultrashort pulses.

The implantation of bismuth during pulsed laser deposition (PLD) are carefully observed and investigated. The implantation range is shown to depend on the energy density used for ablation, which is related to the velocity of the Bi atoms and ions in the plasma.

Spectroscopic ellipsometry (SE) is used to determine the effective linear refractive index, both the real and imaginary parts (n=n-ik), of the nanocomposite system formed by Ag nanocomposites (NCs) embedded in an amorphous aluminum oxide (Al2O3) matrix as a function of Ag metal content. The extinction coefficient shows a maximum around 435 nm that is related to the surface plasmon resonance and the real part of the refractive index undergoes anomalous dispersion, leading to a significant increase of the n value of the composite compared to that of the matrix.

Sequential pulsed laser deposition (PLD) is used to prepare nanocomposite Fe:Al(sub 2)O(sub 3) thin films. The formation of well isolated quasispherical nanocrystals is observed.

Erbium doped Al2O3 films with concentrations up to 6x10(super 20) Er cm(super -3) are prepared in a single process by pulsed-laser deposition. It is explained in terms of shallow Er(super 3+) implantation during deposition.

`Mestizo' pinto bean (Phaseolus vulgaris L.) (Reg. no. CV-185, PI 614097) was developed and released by the Valle del Guadiana Experiment Station of the National Research Institute for Agriculture, Forestry [...]

`Negro Altiplano' opaque black bean (Phaseolus vulgaris L.) (Reg. no. CV-184, PI 614095) was developed and released for commercial production in 1997 by the Valle del Guadiana Experiment Station of [...]

`Negro Sahuatoba' opaque black bean (Phaseolus vulgaris L.) (Reg. no. CV-186, PI 614096) was developed and released for commercial production in 1997 by the Valle del Guadiana Experiment Station of [...]

`Bayacora' pinto bean (Phaseolus vulgaris L.) (Reg. no. CV-187, PI 614098) was developed and released by the Valle del Guadiana Experiment Station of the National Research Institute for Agriculture, Forestry, [...]

The magneto-optical response of nanometric Fe particles with varying size and shape has been studied, both in sputtered single layers and pulsed laser deposited nanocomposite films. The shape of Fe nanoparticles was controlled by varying growth conditions. An effective medium theory for arbitrary particle shapes has been derived and used to simulate the experimentally measured magneto-optical transverse Kerr spectra. The simulations show that the transverse Kerr magneto-optical spectra depend on the particles shape and correlate well with the experimentally determined spectra. From this result, it is deduced that Fe nanoparticles with dimensions down to 3-4 nm keep their bulk magneto-optical constants. On the other hand, large magneto-optical signals are reported in multilayered structures due to interferential effects. Index Terms--Iron nanoparticles, magneto-optics, pulsed laser deposition, sputtering.

The role of size effects on the crystallization of amorphous Ge (a-Ge) in contact with Bi nanocrystals (NCs) is studied using in situ transmission electron microscopy annealing and the Avrami equation. Results show that a-Ge crystallization temperature decreases with increasing Bi metal contract area. The crystal growth of thin Ge layers also occurs through a zig-zag mechanism from one Bi NC to the next.

Pulsed laser deposition (PLD) is a useful method of producing nanocrystalline composites, although its use is limited to producing semiconductor nanocrystals.Spectroscopic ellipsometry (SE) was used to optically characterize composite films with Bi nanocrystals in Ge (BI:Ge films) and A1(sub2)O(sub3) (Bi:A1(sub2)0(sub3) films), produced by PLD in vacuum. A eutectic system of low mutual solubility is formed by Bi and Ge, enabling deposited Bi to form pure isolated and unreacted Bi crystals. SE is shown to be a suitable method of simultaneously determining the effective refractive index, metal content and thickness of thin nanocomposite films.

'Flor de Mayo 2000' common bean (Phaseolus vulgaris L.) (Reg. no. CV-249, PI 639264) was developed and released by the 'Valle del Guadiana' Experiment Station of the National Research Institute [...]

'Negro Vizcaya' shiny black bean (Phaseolus vulgaris L.) (Reg. no. CV-223, PI 633428) was developed and released by the Valle del Guadiana Experiment Station of the National Research Institute for [...]

The common bean (Phaseolus vulgaris L.) cultivar 'Pinto Saltillo' (Reg. no. CV-222, Pl 633427) was developed and released by the Saltillo Agricultural Experiment Station of the Instituto Nacional de Investigaciones [...]