A. L. Rosa

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The applicability of near-field scanning optical microscopy (NSOM) for optical characterization of semiconductors is discussed. The NSOM technique and some of its properties relevant to real-time in-situ measurements are reviewed. Several optical characterization methods widely used in the far-field, including reflectance, reflectance-difference(More)
We study heating and heat dissipation of a single C(60) molecule in the junction of a scanning tunneling microscope by measuring the electron current required to thermally decompose the fullerene cage. The power for decomposition varies with electron energy and reflects the molecular resonance structure. When the scanning tunneling microscope tip contacts(More)
An ultrasonic transducer is incorporated into a near-field scanning optical microscope NSOM to augment its versatility to characterize the properties of layers adsorbed to a sample’s surface. Working under typical NSOM operation conditions, the ultrasonic transducer—attached underneath the sample—demonstrates sufficient sensitivity to monitor the waves(More)
Dip-pen nanolithography (DPN) has attracted increased attention for its ability to generate nanometer-scale patterns on solid surface using an “ink”-coated atomic force microscope (AFM) tip. In contrast to this conventional anchoring-molecules procedure, nanopatterns can also be created by triggering the structural response of the proper substrate. In one(More)
We have developed a complete set of self-consistent charge density-functional tight-binding parameters for ZnX (X = Zn, O, S, Se, Te, Cd, H, C, and N). The transferability of the derived parameters has been tested against Pseudo Potential-Perdew, Burke and Ernzerhof (PP-PBE) calculations and experimental values (whenever available) for corresponding bulk(More)
Characteristic rate variations of carrier processes are imaged using near-field scanning optical microscopy (NSOM). We couple both a visible pump and infrared probe light through a subwavelength aperture to investigate the interband recombination and intraband diffusion of excess carriers in oxidized silicon. Typical values of the locally measured life time(More)
We report the creation of nano-structures via Dip Pen Nanolithography by locally exploiting the mechanical response of polymer thin films to an acidic environment. Protonation of cross linked poly(4-vinylpyridine) (P4VP) leads to a swelling of the polymer. We studied this process by using an AFM tip coated with a pH 4 buffer. Protons migrate through a water(More)
Surface reconstructions and adatom kinetics of silicon on GaN(0001) and (000 ) surfaces are studied by scanning tunneling microscopy, electron diffraction and first-principles calculations. In the low silicon coverage regime a 2×2 structure is observed, and is interpreted in terms of a model consisting of a Ga adatom on a monolayer of 3Ga + 1 Si and a SiGa(More)
Inspired by the fascinating working process of living systems, materials that can respond to external stimuli (mechanical, chemical, optical changes in environmental conditions, etc.) are of enormous interest owing to their applications in a wide range of fields including microfluidic devices, drug delivery, tissue engineering, sensors and actuators. This(More)
5.2.A Uncertainty in the position x and linear momentum p. 5.2.B Relationship between the uncertainty of the energy content E of a pulse and the time t required for the measurement 5.2.B.a Gratings, phasors (addition of multiple waves), conditions for constructive interference, evaluation of the sharpness of the peak of order m. 5.2.B.b Gratings and(More)