Colloidal gold nanoparticles with an average radius of 15 nm have a surface plasmon absorption band at 530 nm. Excitation by laser pulses 450 fs duration, and wavelength 600 or 380 "bleached" the produced transient wings "bleach" spectrum. The was found to similar temporal behavior different wavelengths. Analysis their showed two time constants: 2.5 ps, slower component >50 ps. Laser excitation close leads formation "hot" non-Fermi electronic distribution within colloidal particles....

The electronic dynamics of gold nanocrystals, passivated by a monolayer alkylthiol(ate) groups, were studied transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase samples average particle size 1.9, 2.6, and 3.2 nm distribution less than 10% used. photoexcitation in the intraband (surface plasmon region) leads to heating conduction electron gas its subsequent thermalization through electron−electron electron−phonon interaction. results are analyzed...

Despite their transformative role in our society, oxide glasses remain brittle. Although extrinsic postprocessing techniques can partially mitigate this drawback, they come with undesirable side effects. Alternatively, topological engineering offers an attractive option to enhance the intrinsic strength and damage resistance of glass. On basis approach, we report here discovery a novel melt-quenched lithium aluminoborate glass featuring highest crack ever reported for bulk Relying on...

The relaxation dynamics of charge carriers in 4 nm CdS colloidal quantum dots are studied by means picosecond time-resolved fluorescence and femtosecond transient absorption experiments. We also the effects adsorption viologen derivatives as electron acceptors on surface these particles. From experimental measurements, we reached a model electron-hole nanoparticles consistent with previous proposals. In particular, have confirmed that trapping particles is slower than hole (30 ps versus few...

The dynamics of all-trans and 13-cis retinal protonated Schiff base (RPSB) were studied in different solvents by means picosecond transient spectroscopy. decay time the excited state absorption was found to be wavelength dependent due contribution faster stimulated emission. emission has a lifetime 2.5−4 ps while is biexponential with lifetimes 10−12 ps. fluorescence quantum yield strongly temperature dependent, but viscosity small effect on both excited-state yield. This leads conclusion...

We present the results of two-pump and probe femtosecond experiments designed to follow relaxation dynamics lowest excited state (S 1 ) populated by different modes. In first mode, a direct 0 → S radiative excitation ground is used. second an indirect used where use two laser pulses with colors delay times between them. The pulse excites transition whereas n transition. nonradiative from populates state. Our suggest that relaxes faster when nonradiatively than pumped directly excitation....

The quantum yield of photoisomerization and the energy content K intermediate in photocycle bacteriorhodopsin its mutants D85N, R82Q, D212N deionized blue bR were measured. Transient optical absorption photoacoustic spectroscopy with excitation using 400 fs laser pulse combined to obtain results. spectroscopic characteristics excited state, J intermediates mutants, determined. presence both 13-cis all-trans isomers ground state light-adapted makes extraction for each isomer difficult. Thus,...

Subpicosecond photoexcitation of CdS/HgS/CdS quantum dot well nanoparticles at wavelengths shorter than their interband absorption (390 nm) leads to a photobleach spectrum longer (440−740 nm). The changes and its maximum red-shifts with delay time. These results are explained by the rapid quenching initially formed laser-excited excitons two types energy acceptors (traps); one is proposed be due CdS molecules CdS/HgS interface, other trap that present in well. excitation as formation decay...

A double frequency overtone of the fundamental N–H bond related vibration was found to dominate optical loss in 1.5–1.6 μm range high index GeSiON-based planar waveguides deposited by plasma-enhanced chemical vapor deposition using hydrogen-based precursors. The bond-related absorption and its were measured be ∼560 cm−1 1.8 cm−1, respectively, resulting their ratio 310±10. loss, extracted from analysis N–H-related is consistent with directly waveguide structures. It shown that deuterated...

Fiber-based cylindrical light diffusers are often used in photodynamic therapy to illuminate a luminal organ, such as the esophagus. The made of plastic and suffer from short diffusion lengths low transmission efficiencies over broad spectrum. We have developed Fibrance^TM, glass-based fiber optic diffuser which can 0.5 cm 10 meters wavelength range. With these longer illumination lengths, variety other medical applications possible beyond therapy. present number for Fibrance...

Background and Objectives Hospital‐acquired infections (HAIs) multidrug resistant bacteria pose a significant threat to the U.S. healthcare system. With dearth of new antibiotic approvals, novel antimicrobial strategies are required help solve this problem. Violet‐blue visible light (400–470 nm) has been shown elicit strong effects toward many pathogens, including representatives ESKAPE bacterial which have high propensity cause HAIs. However, phototherapeutic solutions prevention or...

The method of cavity ringdown spectroscopy (when a tunable pulsed optical parametric oscillator was used) extended for the loss evaluation in thin films (2-20-microm thickness). technique applied two key telecommunication wavelength ranges 1260-1330 and 1480-1650 nm. measurement sensitivity determined to be 50 ppm (5 x 10(-5)). results polymer are close correlation with conventional spectrophotometric data propagation planar waveguides. Films greater thickness better quality expected provide...

Analysis of laser assisted frit sealing processes for high CTE > 5x10 -6 /°C (coefficient thermal expansion) glasses was done.The method is based on the fusion two with a low melting point glass frit.This used when sensitive materials such as OLED (organic light emissive device) are present in package.The selected to be highly absorbent at wavelength, while transparent wavelength.It found that conditions optimized (< /°C) glass, suitable display devices, produces very poor results.The issue...

We describe the design of thin, ~ 100-180 micron diameter, optical silica fibers for illumination. The fiber has a core with specially engineered scattering centers to scatter light through walls across wide wavelength range.

Data obtained previously in our lab for the quantum yield retinal photoisomerization and energy content of K-intermediate formed bacteriorhodopsin its mutants (bR) photocycle are reexamined using time-resolved transient spectroscopy laser-induced photoacoustic spectroscopy. In present experiment both nanosecond subpicosecond laser pulses used excitation, with different reference compounds. From these new results it can be concluded that CoCl2 as a compound gives large amount prompt heat...

Using time-resolved optical hole (oh)-burning techniques with femtosecond lasers, the time dependence of spectral diffusion oh is examined for both CdS quantum dot (QD) and CdS/HgS/CdS well (QDQW) nanoparticles. It found that nonradiative relaxation at least 3 orders magnitude slower in QDQW than QD system. Analysis second derivative broad transient bleach spectrum system 1.6−2.5 eV energy region 50 fs delay to have a minimum 2.1 eV, corresponding radiative probability. Around this energy,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-assembled ion-pair complexes between porphyrins and bipyridinium species: picosecond dynamics of charge recombinationS. L. Logunov Michael A. J. RodgersCite this: Phys. Chem. 1992, 96, 22, 8697–8700Publication Date (Print):October 1, 1992Publication History Published online1 May 2002Published inissue 1 October 1992https://pubs.acs.org/doi/10.1021/j100201a009https://doi.org/10.1021/j100201a009research-articleACS PublicationsRequest reuse...

The heating effect in highly bent singlemode optical fibres under high power conditions was studied. It found that of the coating depends on bend radius and type telecommunication fibre used. detected only occurred at diameters much smaller than recommended for normal deployment.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubnanosecond dynamics of a naphthalene-oxygen exciplexStephan L. Logunov and Michael A. J. RodgersCite this: Phys. Chem. 1992, 96, 7, 2915–2917Publication Date (Print):April 1, 1992Publication History Published online1 May 2002Published inissue 1 April 1992https://pubs.acs.org/doi/10.1021/j100186a025https://doi.org/10.1021/j100186a025research-articleACS PublicationsRequest reuse permissionsArticle Views92Altmetric-Citations23LEARN ABOUT THESE...

We have systematically analyzed the excess scattering in a relatively large index optical fiber operating single mode regime. A mathematical model based on theory of plane waves from randomly perturbed core-clad interface is presented that predicts confined within small angle forward direction. An experimental system developed can measure angular distribution over ∼0°–180°. Excellent agreement between computed and measured observed multiple wavelengths wide range. The spectral its response...

We describe a novel process of laser-assisted fabrication surface structures on doped oxide glasses with heights reaching 10 - 13% the glass thickness. This effect manifests itself as swelling irradiated portion glass, which occurs in wide range compositions. The extent such depends base composition. Doping Fe, Ti, Co, Ce, and other transition metals allows for adjusting absorption maximizing feature size. In case bumps grown borosilicate glasses, we observe reversible bump height can...

Abstract The paper reviews optical fibers with nano-engineered features and methods to fabricate them. These have regions comprising of randomly distributed voids which provide unique properties for designing next generation fibers. Discussion impact void morphology on fiber is presented, along the control characteristics. Use different applications (ultra-low bend loss single mode fiber, quasi-single endless single-mode light diffusing fibers) discussed attributes in these highlighted.