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1.
Artigo em Inglês | MEDLINE | ID: mdl-32615007

RESUMO

Phosphagallenes (1 a/1 b) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6-i-Pr2 C6 H3 )]2 ). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a, which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound (2) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H2 and forms a 1:1 adduct with CO2 .

2.
Chemistry ; 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32495945

RESUMO

We describe the reactivity of two linkage isomers of a boryl-phosphaethynolate, [B]OCP and [B]PCO (where [B] = N , N '-bis(2,6-diisopropylphenyl)-2,3-dihydro-1 H -1,3,2-diazaboryl), towards tris (pentafluorophenyl)borane (BCF). These reactions afforded three constitutional isomers all of which contain a phosphaalkene core. [B]OCP reacts with BCF via a 1,2 carboboration reaction to afford a novel phosphaalkene, E -[B]O{(C 6 F 5 ) 2 B}C=P(C 6 F 5 ), which subsequently undergoes a rearrangement process involving migration of both the boryloxy and pentafluorophenyl substituents to afford Z -{(C 6 F 5 ) 2 B}(C 6 F 5 )C=PO[B]. By contrast, [B]PCO undergoes a 1,3-carboboration process accompanied by migration of the N , N '-bis(2,6-diisopropylphenyl)-2,3-dihydro-1 H -1,3,2-diazaboryl to the carbon centre.

3.
Chem Commun (Camb) ; 55(48): 6842-6845, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31120468

RESUMO

We describe the reaction of a phosphaethynolato-borane [B]OCP ([B] = N,N'-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl) with the organometallic nucleophile Na[Cp*Fe(CO)2] (Cp* = pentamethylcyclopentadienyl). The electrophilic character of [B]OCP allows for a new route towards the formation metal-phosphorus bonds affording a metallophosphaalkene that can be functionalised at both the oxygen and phosphorus atoms depending on the reagents employed.

4.
Angew Chem Int Ed Engl ; 57(8): 2188-2193, 2018 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-29316112

RESUMO

The synthesis and characterization of a stable phosphaethynolatoborane, [B]OCP (1, [B]=N,N'-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), is described. The increased triple bond character of the P-C bond in 1 relative to the free ion (PCO- ) is probed in a series of reactivity studies. Compound 1 readily dimerises in donor solvents to afford a cyclic five-membered 6π-aromatic compound, cyclo-P2 {C[B]}O{CO[B]} (2), which decarbonylates on UV irradiation. By contrast the nickel-mediated dimerisation of 1 affords the isomeric diphosphacyclobutene [P(CO[B])]2 . When 1 is reacted with organolithium reagents such as MesLi (Mes=2,4,6-trimethylphenyl), the boryl moiety shifts and the formation of the lithoxy-boryl-phosphaalkene [LiOC[B]P(Mes)]2 was observed. The reactivity of this species towards electrophiles is also described.

5.
Appl Opt ; 53(7): 1363-80, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24663366

RESUMO

The design, characteristics, and first test flight results are described of the Portable Remote Imaging Spectrometer, an airborne sensor specifically designed to address the challenges of coastal ocean remote sensing. The sensor incorporates several technologies that are demonstrated for the first time, to the best of our knowledge, in a working system in order to achieve a high performance level in terms of uniformity, signal-to-noise ratio, low polarization sensitivity, low stray light, and high spatial resolution. The instrument covers the 350-1050 nm spectral range with a 2.83 nm sampling per pixel, and a 0.88 mrad instantaneous field of view, with 608 cross-track pixels in a pushbroom configuration. Two additional infrared channels (1240 and 1610 nm) are measured by a spot radiometer housed in the same head. The spectrometer design is based on an optically fast (F/1.8) Dyson design form coupled to a wide angle two-mirror telescope in a configuration that minimizes polarization sensitivity without the use of a depolarizer. A grating with minimum polarization sensitivity and broadband efficiency was fabricated as well as a slit assembly with black (etched) silicon surface to minimize backscatter. First flight results over calibration sites as well as Monterey Bay in California have demonstrated good agreement between in situ and remotely sensed data, confirming the potential value of the sensor to the coastal ocean science community.


Assuntos
Aeronaves/instrumentação , Monitoramento Ambiental/instrumentação , Tecnologia de Sensoriamento Remoto/instrumentação , Água do Mar/análise , Água do Mar/química , Análise Espectral/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Miniaturização , Oceanos e Mares , Projetos Piloto
6.
Opt Express ; 16(14): 10200-7, 2008 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-18607427

RESUMO

Using an optical vortex coronagraph and simple adaptive optics techniques, we have made the first convincing demonstration of an optical vortex coronagraph that is coupled to a star gazing telescope. We suppressed by 97% the primary star of a resolvable binary system, Cor Caroli. The stars had an angular separation of 1.9lambda/D at our imaging camera. The secondary star suffered no suppression from the vortex lens.

7.
Opt Express ; 16(12): 9087-96, 2008 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-18545620

RESUMO

We present an optical design for an airborne imaging spectrometer that addresses the unique constraints imposed by imaging the coastal ocean region. A fast (F/1.8) wide field system (36 degrees) with minimum polarization dependence and high response uniformity is required, that covers the spectral range 350-1050 nm with 3 nm sampling. We show how these requirements can be achieved with a two-mirror telescope and a compact Dyson spectrometer utilizing a polarization-insensitive diffraction grating.


Assuntos
Monitoramento Ambiental/instrumentação , Aumento da Imagem/instrumentação , Modelos Teóricos , Refratometria/instrumentação , Análise Espectral/instrumentação , Água/química , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Oceanos e Mares , Espalhamento de Radiação
8.
J Biomed Opt ; 12(1): 014036, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17343511

RESUMO

Retinal imaging spectroscopy can provide functional maps using chromophore spectra. For example, oxygen saturation maps show ischemic areas from diabetes and venous occlusions. Obtaining retinal spatial-spectral data has been difficult due to saccades and long data acquisition times (>5 s). We present a snapshot imaging spectrometer with far-reaching applicability that acquires a complete spatial-spectral image cube in approximately 3 ms from 450 to 700 nm with 50 bands, eliminating motion artifacts and pixel misregistration. Current retinal spectral imaging approaches are incapable of true snapshot operation over a wide spectral range with a large number of spectral bands. Coupled to a fundus camera, the instrument returns true color retinal images for comparison to standard fundus images and for image validation while the patient is still dilated. Oxygen saturation maps were obtained with a three-wavelength algorithm: for healthy subjects arteries were approximately 95% and veins 30 to 35% less. The instrument is now undergoing clinical trials.


Assuntos
Angiofluoresceinografia/instrumentação , Aumento da Imagem/instrumentação , Microscopia de Fluorescência por Excitação Multifotônica/instrumentação , Oximetria/instrumentação , Retinoscópios , Adulto , Desenho de Equipamento , Análise de Falha de Equipamento , Angiofluoresceinografia/métodos , Humanos , Aumento da Imagem/métodos , Masculino , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Oximetria/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
Appl Opt ; 46(9): 1397-407, 2007 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-17334428

RESUMO

We investigate the behavior of imperfect band-limited occulting masks in a high-contrast imaging system through modeling and simulations. Grayscale masks having 1D Sinc(2) (linear-Sinc(2)) amplitude transmission coefficient (Sinc(4) intensity transmittance) profiles as well as optical density and wavelength-dependent parasitic phases are considered occulters. We compare the behaviors of several, slightly different occulter transmittance profiles by evaluating the contrast performance of the high-contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory (JPL). These occulters include a measured occulter, a standard Sinc(2) occulter, and several of its variations. We show that when an occulting mask has a parasitic phase, a modified Sinc(2) transmittance profile works much better than the standard Sinc(2) mask. We examine the impact of some fabrication errors of the occulter on the HCIT's contrast performance. We find through modeling and simulations that starlight suppression by a factor of more than 10(10) is achievable at least monochromatically on the HCIT with the occulting mask and the optics currently being used on the testbed. To the best of our knowledge, this is the first time that we investigate the behavior of a real (or fabricated) focal plane occulting mask in a high-contrast imaging system. We also briefly describe the approach used at JPL in fabricating a grayscale occulting mask and characterizing its transmittance and phase profiles.

10.
Appl Opt ; 45(9): 1898-908, 2006 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-16579558

RESUMO

Experimental results are presented for a computed tomography imaging spectrometer (CTIS) with imposed spatial-spectral modulation on the image scene. This modulation structure on the CTIS tomographic dispersion created substantial gains in spectral reconstruction resolution after standard iterative, nonlinear, inversion techniques were used. Modulation limits system ambiguities, so high-frequency spectral and low-frequency spatial scene data could be recovered. The results demonstrate how spatial modulation acts as a high-frequency spectral deconvolver for the snapshot hyperspectral imager technology.

11.
Opt Lett ; 30(12): 1464-6, 2005 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-16007775

RESUMO

Snapshot hyperspectral imaging simultaneously acquires spatial and spectral information about a scene. We report on the first, to our knowledge, all-reflective snapshot hyperspectral imager in the form of a computed tomography imaging spectrometer (CTIS). The reflective design allows for instrument simplicity for applications in the ultraviolet and infrared. To realize a CTIS in a reflective Offner configuration, a reflective two-dimensional computer-generated hologram grating is fabricated on a convex spherical substrate by direct-write electron-beam lithography. Furthermore, a reconfigurable reflective field stop is implemented with a micromirror array to provide high-contrast spatial-spectral filtering, region-of-interest selection, and spatial structure formation.

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