JESSICA DIPOLD

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Agora exibindo 1 - 10 de 26
  • Artigo IPEN-doc 30231
    Tunable visible light and energy transfer mechanism in Tm3+ and silver nanoclusters within co-doped GeO2-PbO glasses
    2023 - NISHIMURA, MARCOS V. de M.; AMARO, AUGUSTO A.; BORDON, CAMILA D. da S.; DIPOLD, JESSICA; WETTER, NIKLAUS U.; KASSAB, LUCIANA R.P.
    This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.
  • Artigo IPEN-doc 30193
    Random lasers
    2023 - WETTER, NIKLAUS U.; VIEIRA, RENATO J.R.; SILVA, DANILO M. da; JORGE, KELLY C.; JIMENEZ-VILLAR, ERNESTO; GIEHL, JULIA M.; MIRANDA, ADRIANA R. de; DIPOLD, JESSICA
    Random lasers offer advantages such as low-cost fabrication and robustness in harsh environments and have applications in sensing, imaging, communications, and security. Our current research focuses on advanced materials, active control techniques, integration with other photonic structures, and exploration of Anderson localization and polydisperse effects. Coherent feedback in cavity-enhanced random lasers is discussed as means to achieve specific emission characteristics, and emission at 1300 nm is shown for the first time.
  • Artigo IPEN-doc 30185
    Random laser emission in Nd3+ doped tellurite glass
    2023 - DIPOLD, JESSICA; BORDON, CAMILA D.S.; MAGALHAES, EVELLYN S.; KASSAB, LUCIANA R.P.; JIMENEZ-VILLAR, ERNESTO; WETTER, NIKLAUS U.
    Random lasers are easier and cheaper to manufacture than regular ones, being made of several materials such as polymers, powders or dyes. Glass random lasers have been rarely studied due to their inhomogeneous broadened emission and low damage threshold. Here, we study Nd 3 +doped Te0 2 -ZnO-Al 2 0 3 glasses with different concentrations of rare-earth doping (4 wt.%, 8 wt.% and 16 wt.%). Emission intensity per pump fluence and fluorescence decay time measurements showed the potential of these glasses for random laser applications in the near-infrared region.
  • Resumo IPEN-doc 30052
    Waveguide amplifiers produced by femtosecond laser in doped heavy metal glasses
    2023 - ROSSI, WAGNER de; WETTER, NIKLAUS U.; DIPOLD, JESSICA; BORDON, CAMILA D.S.; KASSAB, LUCIANA R.P.
    Waveguides are very suitable structures for integrating optics in miniaturized systems such as those involved in microfluidics. With them, it is possible to stimulate reactions using light and collect information from optical signals from specific points of a given system. Thus, for example, it is possible to transport light from an external source to a microreactor within a microfluidic system and/or collect the emission of any reagent or reaction from any point in the system. In this context, several kinds of research have been carried out for the development of waveguides in transparent materials suitable for use in microfluidic systems such as lab-on-a-chip. A widely used way of producing such guides is through the focusing of ultrashort laser pulses (fs) inside transparent materials. In this case, the intensity is adjusted so that the absorbed energy is sufficient to change the crystalline arrangement in the focal region, but not enough to cause catastrophic damage, that is, that there is no rupture of bonds between atoms. This change in the local arrangement of atoms (or ions) leads to a localized change in the index of refraction, which can be used to refract light. If a line of such regions, or points, has an index of refraction greater than that of the surrounding medium, then it is possible to guide light within it as in an optical fiber. If the index of refraction changes to a value less than that of the neighboring medium, then it is only possible to guide the light between two or more of these lines. This work describes the development and characterization of waveguides produced with two lines by processing heavy metal oxide glasses with a femtosecond laser. Tellurite (TeO2-ZnO) and germanate (GeO2-PbO) glasses were used [1,2], pure and also doped with rare earth. Raman spectroscopy shows a decrease in the photoinduced refractive index, from -7.4x10-3 to 1x10-5, depending on the material and processing conditions. Thus, it is not possible to guide light inside a single line and, therefore, two of these lines were used for this purpose, with the guidance being done between them. The work details the laser machining process, the physical and spatial characteristics of the guides produced, the characteristics of the guided spatial mode, such as the M2 parameter, the transmission losses, and the gain obtained when glasses doped with rare earths are used.
  • Artigo IPEN-doc 30050
    Raman enhancement induced by localization of light (TiO2@Silica plus silica nanoparticles)
    2023 - DIPOLD, JESSICA; WETTER, NIKLAUS U.; FREITAS, ANDERSON Z.; MARQUES, FRANCISCO C.; DOGARIU, ARISTIDE; JIMENEZ-VILLAR, ERNESTO
    Strong enhancement of the Raman signal is observed in ethanol suspension of TiO2@Silica, being stronger as the TiO2@Silica filling fraction is increased above threshold, and when silica nanoparticles are added.
  • Artigo IPEN-doc 30047
    Direct nanoplastics detection below the diffraction limit using micro Raman
    2023 - BERECZKI, ALLAN; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS
    Raman spectra of polystyrene nanoparticles of 50 nm diameter were directly measured using micro-Raman spectroscopy. Data analysis demonstrated that particles as small as 20 nm could be directly measured with this simple and robust technique.
  • Artigo IPEN-doc 30037
    Sub-10 nm nanoparticle detection using multi-technique-based micro-raman spectroscopy
    2023 - BERECZKI, ALLAN; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS U.
    Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nanosized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO2 nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force Microscopy
  • Artigo IPEN-doc 30036
    (U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation
    2023 - MUNOZ, PATRICIO; ILAVSKY, JAN; NEWVILLE, MATTHEW; WETTER, NIKLAUS U.; LOURENÇO, RAFAEL A.; ANDRADE, MARCELO B. de; MARTINS, TEREZA S.; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; SILVA, LUIS C.C. da; OLIVEIRA, CRISTIANO L.P.
    This study characterizes the microstructure and mineralogy of 132 (ODP sample), 1000 and 1880 million-year-old chert samples. By using ultra-smallangle X-ray scattering (USAXS), wide-angle X-ray scattering and other techniques, the preservation of organic matter (OM) in these samples is studied. The scarce microstructural data reported on chert contrast with many studies addressing porosity evolution in other sedimentary rocks. The aim of this work is to solve the distribution of OM and silica in chert by characterizing samples before and after combustion to pinpoint the OM distribution inside the porous silica matrix. The samples are predominantly composed of alpha quartz and show increasing crystallite sizes up to 33 5 nm (1 standard deviation or SD). In older samples, low water abundances (0.03%) suggest progressive dehydration. (U)SAXS data reveal a porous matrix that evolves over geological time, including, from younger to older samples, (1) a decreasing pore volume down to 1%, (2) greater pore sizes hosting OM, (3) decreasing specific surface area values from younger (9.3 0.1 m2 g 1 ) to older samples (0.63 0.07 m2 g 1 , 1 SD) and (4) a lower background intensity correlated to decreasing hydrogen abundances. The pore-volume distributions (PVDs) show that pores ranging from 4 to 100 nm accumulate the greater volume fraction of OM. Raman data show aromatic organic clusters up to 20 nm in older samples. Raman and PVD data suggest that OM is located mostly in mesopores. Observed structural changes, silica–OM interactions and the hydrophobicity of the OM could explain the OM preservation in chert.
  • Artigo IPEN-doc 29785
    1337 nm emission of a Nd3+-doped TZA glass random laser
    2023 - DIPOLD, JESSICA; BORDON, CAMILA D.S.; MAGALHAES, EVELLYN S.; KASSAB, LUCIANA R.P.; JIMENEZ-VILLAR, ERNESTO; WETTER, NIKLAUS U.
    Random lasers have been studied using many materials, but only a couple have used glass matrices. Here, we present a study of zinc tellurite and aluminum oxide doped with different percentages of neodymium oxide (4 wt.%, 8 wt.%, and 16 wt.%) and demonstrate for the first time random laser action at 1337 nm. Laser emission was verified and the laser pulse’s rise time and input–output power slope were obtained. A cavity composed of the sample’s pump surface and an effective mirror formed by a second, parallel layer at the gain-loss boundary was probably the main lasing mechanism of this random laser system. The reason for the absence of emission at 1064 nm is thought to be a measured temperature rise in the samples’ active volume.
  • Artigo IPEN-doc 29716
    Silver nanoclusters tunable visible emission and energy transfer to Yb3+ Ions in co-doped GeO2-PbO glasses for photonic applications
    2023 - AMARO, AUGUSTO A.; MATTOS, GUILHERME R. da S.; NISHIMURA, MARCOS V. de M.; DIPOLD, JESSICA; WETTER, NIKLAUS U.; KASSAB, LUCIANA R.P.
    This work investigates the optical properties of Yb3+ ions doped GeO2 -PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices.