Pulsed Ruby Laser Research Articles

Transvascular delivery of talaporfin sodium to subcutaneous tumors in mice by nanosecond pulsed laser-induced photomechanical waves

BackgroundWe previously developed a site-specific transvascular drug delivery system (DDS) based on photomechanical waves (PMWs) or laser-induced stress/shock waves (LISWs). In this study, we investigated the validity of this method to deliver a clinical photosensitizer, talaporfin sodium (TS), to subcutaneous tumors in mice and to enhance the efficacy of photodynamic therapy (PDT). MethodsTS solution (2.5 mg/kg) was intravenously injected into mice. Immediately thereafter, PMWs were applied to the tumor by irradiating a laser target with a Q-switched ruby laser pulse (0.8 J/cm2). Five hours after TS administration, some tumors were excised to evaluate the depth distribution of the delivered TS under a fluorescence microscope. Other tumors were subjected to PDT by irradiating the tissues with a 665 nm continuous-wave laser diode (75 mW/cm2, 667 s) at this timepoint. The effects of PDT were evaluated on the basis of the two primary therapeutic mechanisms of TS-mediated PDT: i) damage to tumor cells and ii) damage to endothelial cells of tumor vessels, i.e., the vascular shutdown effect on tumors. ResultsPMW application significantly increased the accumulation of TS in the tumor parenchyma but not in the tumor vessel walls; the endothelial cell junctions of tumor vessels should be the route of TS delivery enhanced by PMWs. Thus, as a result of PMW application followed by PDT, while the vascular shutdown effect on the tumors was not enhanced, direct damage to the tumor cells was increased, resulting in significant tumor growth retardation without body weight loss for 7 days after treatment.

La Vie En Rose - Danièle Sylvie Aron-Rosa

La Vie En Rose - Danièle Sylvie Aron-Rosa

Laser annealing of epitaxial CaF2 films on Si

Nanosecond time-resolved reflectivity and transmission changes in CaF2/Si(111) structures were measured to study the phase transitions, surface modification and radiolysis induced by nanosecond ruby laser pulses. The Si lattice heating up to the melting point leads to the nanohills formation on the surface of the structure, the height of which does not exceed 100 nm with the average base diameter of 360 nm and the surface density of 2•108cm– 2. The Raman scattering and energy-dispersive X-ray spectroscopy data indicate that the nanohills contain cavities inside them, and they are filled with the gas of Si2F6 molecules. The shell of the nanohills, obviously, consists of calcium oxide.

Two-Photon Excited Luminescence in Polyethylene and Polytetrafluoroethylene

Luminescence spectra of polytetrafluoroethylene (Teflon), a Teflon film, and a polyethylene film are registered in wide wavelength range under excitation by radiations with different wavelengths. For the first time, we detect two-photon-excited luminescence in polymers at low intensity of exciting light. In Teflon, we also register luminescence in the blue range under excitation by ruby laser pulses.

Stimulated Raman scattering of light in suspension of diamond microparticles in ethanol and in water.

The spectra of stimulated Raman scattering of light in ethanol and in water suspensions containing diamond microparticles with sizes 0.2-0.3μm were investigated. An excitation radiation source was a pulsed ruby laser with a generation wavelength λ0=694.3nm, a pulse duration τp≈20ns, a maximum beam energy of Emax=0.6J, a spectral width Δν=0.015cm-1, and a beam divergence 3.5·10-4rad. For the first time, the observation of stimulated Raman scattering of light at a boson peak in suspension of diamonds microcrystals with close sizes (0.2-0.3μm) in a liquid is reported. The corresponding spectra were recorded using a Fabry-Perot interferometer. In this case, the frequency shift of the stimulated Stokes Raman scattering depended on the size of the diamond microparticles introduced into the liquid and amounted to ~1cm-1. In addition, stimulated Raman scattering by a fundamental optical mode with a frequency shift ν=1331cm-1 was observed. In this case, the Raman spectra were recorded using a small-sized spectrometer with a multi-element receiver, detecting radiation in the range of 200-1000nm. At a sufficiently high intensity of the exciting radiation, the Stokes and anti-Stokes satellites were simultaneously present in the spectrum of stimulated Raman scattering. The obtained results on stimulated scattering of diamond microparticles in liquids are of interest for estimating the sizes of microcrystals from scattering spectra at a boson peak, as well as for creating a frequency comb of emitters based on stimulated Raman scattering with a large frequency shift.

Наносекундное воздействие интенсивного лазерного излучения на тонкие плёнки TiAlN

The spectral dependencies (λ = 0.35-1.0 μm) of the transmittance and reflectivity (R) of TiAlN thin films deposited on glass and Si substrates by magnetron sputtering technique have been measured. The TiAlN/Si films of 0.5 μm thickness were irradiated by single nanosecond (70 ns) ruby laser pulses in order to study the influence of laser-induced thermophysical processes in TiAlN on its R(t) dynamics at the wavelengths λ1 = 0.53 and λ2 = 1.06 μm of probing radiation, and on the state of laser irradiation zones, which was studied by optical and scanning electron microscopy. The observed in the experiment and connected with the pulsed heating dynamics changes of R - increase at λ1 and decrease at λ2 amplifies as the irradiation energy density W approaches to the threshold of laser ablation of the nitride ~ 1 J/cm2. Laser-induced thermophysical processes, occurring at W = 0.6-0.9 J/cm2, lead to a specific modification of the TiAlN layer with the formation of a net of cracks due to thermal stresses arising during the laser pulse. The increase of W leads to the formation of a more developed net/cellular structure of the film with a smaller average size of cells.

Stimulated low-frequency Raman scattering in biological nanoparticles suspensions

The interaction of electromagnetic radiation with nanoscale particles systems (including suspension of metallic dielectric and semiconductor nanoparticles, biological nanostructures, etc.) can lead to various non-linear effects, in particular, to the stimulated low-frequency Raman scattering (SLFRS). It can provide important information about investigated system elastic properties. In the present study low-frequency vibrational modes in different biological nanoparticles systems were investigated, such as tobacco mosaic viruses (TMV), two types of potato viruses (PVX and PVA), cauliflower mosaic virus (CaMV), human and bovine serum albumin (HSA and BSA) in Tris-HCl pH7.5 buffer and in water. 20 ns ruby laser pulses were used for excitation. SLFRS frequency shifts, corresponding to acoustic eigenfrequencies of the samples were registered by Fabri-Perot interferometers. Conversion efficiency and threshold were also measured for the first time. SLFRS can be applied for nanoobjects identification and effective impact on biological nanoparticles systems.

Crystallization of submicron amorphous hydrogenated silicon films with different hydrogen concentration by nanosecond ruby laser irradiation

Pulse laser annealing remains an actual problem aimed to crystallization of amorphous films on nonrefractive substrates. But, the most previous works studied laser crystallization of relatively thin (<300 nm) a-Si:H films and mainly used excimer lasers. But, excimer lasers are not suitable for crystallization of submicron a-Si:H films due to low penetration depth in a-Si:H at such wavelengths. The problem can be resolved by using lasers with longer wavelengths. The desirable result of crystallization also depends on the choice of proper laser fluence, which is different for films with different hydrogen concentrations. In this work, the processes of a pulsed ruby laser induced crystallization of submicron (0.7 μm) amorphous hydrogenated silicon films with different hydrogen concentrations (2, 12, and 39 at. %) by different laser fluences were investigated. The films were prepared on glass substrates by plasma enhanced chemical vapor deposition technique followed by isothermal annealing in nitrogen atmosphere. The laser annealing (λ = 694 nm) was carried out at a pulse duration of 80 ns (full width at half-maximum) in the fluence range from 0.6 to 2.1 J/cm2. The laser fluence thresholds for surface area crystallization were found for different hydrogen concentrations in the films. The increase of hydrogen concentration leads to an increase of the threshold energy density (laser fluence) for surface area crystallization due to a decrease of light absorption in the films with a higher hydrogen concentration. Also, it was shown that ruby laser radiation can penetrate and partially crystallize the full depth of the submicron a-Si:H film, but the problem of homogeneity remains.Pulse laser annealing remains an actual problem aimed to crystallization of amorphous films on nonrefractive substrates. But, the most previous works studied laser crystallization of relatively thin (<300 nm) a-Si:H films and mainly used excimer lasers. But, excimer lasers are not suitable for crystallization of submicron a-Si:H films due to low penetration depth in a-Si:H at such wavelengths. The problem can be resolved by using lasers with longer wavelengths. The desirable result of crystallization also depends on the choice of proper laser fluence, which is different for films with different hydrogen concentrations. In this work, the processes of a pulsed ruby laser induced crystallization of submicron (0.7 μm) amorphous hydrogenated silicon films with different hydrogen concentrations (2, 12, and 39 at. %) by different laser fluences were investigated. The films were prepared on glass substrates by plasma enhanced chemical vapor deposition technique followed by isothermal annealing in nitrogen atmosph...

Laser excitation of gigahertz vibrations in Cauliflower mosaic viruses’ suspension

The interaction of laser pulses with the Cauliflower mosaic virus (CaMV) in a Tris-HCl pH7.5 buffer is investigated. 20 ns ruby laser pulses are used for the excitation. Spectra of the light passing through the sample and reflected from it are registered with the help of a Fabri–Perot interferometer. Stimulated low-frequency Raman scattering (SLFRS) in a CaMV suspension is registered. The SLFRS frequency shift, conversion efficiency and threshold are measured for the first time, to the best of our knowledge.

2p-YH-1 大出力パルス・ルビーレーザー光照射による物質合成

2p-YH-1 大出力パルス・ルビーレーザー光照射による物質合成

Stimulated low-frequency Raman scattering in plant virus suspensions

The study deals with laser pulse interaction with plant viruses: we investigated tobacco mosaic virus (TMV) and two types of potato viruses (PVX and PVA) in Tris-HCl pH7.5 buffer and in water. We used 20 ns ruby laser pulses for excitation. We employed Fabry–Pérot interferometers to record spectra of the light passing through the sample and reflected from it. For TMV and PVX in Tris-HCl pH7.5 buffer, same as for PVA in water, we observed additional spectral lines corresponding to the stimulated low-frequency Raman scattering (SLFRS). We believe we were the first to measure SLFRS frequency shifts, conversion efficiency and threshold. High conversion efficiency of the scattered light is evidence of laser pulses efficiently exciting gigahertz vibrations in viruses. SLFRS can be used to identify and affect biological nanoparticles.

Stimulated low-frequency Raman scattering in a suspension of tobacco mosaic virus

The interaction of laser pulses with tobacco mosaic virus (TMV) in Tris-HCl pH7.5 buffer and in water has been investigated. Ruby laser pulses of 20 ns duration have been used for excitation. The spectrum of the light passing through the sample was registered with the help of a Fabry–Perot interferometer. In the case of TMV in water we observed in the spectrum only one line of the exciting laser light, but for TMV in Tris-HCl pH7.5 buffer a second line appeared, corresponding to stimulated low-frequency Raman scattering (SLFRS) on the breathing radial mode of TMV. The frequency shift of the SLFRS by 2 cm−1 (60 GHz), the conversion efficiency and the threshold are measured for the first time to the best of our knowledge.

Frozen ZnS Aqueous Suspension Nonlinear Optical Properties

The study of nonlinear effects, caused by nanosecond laser pulses’ impact on the frozen ZnS nanoparticles’ suspension, is presented. Laser pulses excite strong nanoparticles’ coherent vibrations in the near-terahertz range which lead to different nonlinear effects: X-ray emission, stimulated low-frequency Raman scattering, and luminescence. X-ray emission was observed as bright spots on the special X-ray film. This provides evidence that an X-ray propagates with narrow beams. Stimulated low-frequency Raman scattering is a result of light scattering by acoustic vibrations of nanoparticles. Its frequency shift corresponds to the nanoparticles’ eigenvibration frequencies and depends on the sample material and particle’s dimension. It was measured with the help of a Fabri-Perot interferometer in the range of dispersion $$16.67\,\hbox {cm}^{-1}$$ . For ZnS, the first Stokes component frequency shift is equal to 465 GHz. Under excitation by 20 ns ruby laser pulses, the luminescence of the frozen ZnS nanoparticles’ suspension was observed in two bands located at 480 nm and 510 nm. Its duration was more than 3 s.

Synchrotron Radiation in France: The Early Years

At the beginning of the 1960s, outside the U.S., very few electron synchrotrons existed and synchrotron light studies were still in their infancy. At the Sorbonne in Paris, Yvette Cauchois, the Director of the Laboratoire de Chimie Physique, a well-known scientist specializing in the low X-ray energy range, had contacts with U.S. pioneers in synchrotron light studies such as L.G. Parrat and D.H. Tomboulian. She evaluated the potential of this new radiation source able to produce the photon energy range bridging UV and X-ray, a range at this time difficult to produce in the laboratory by windowless X-ray tubes or hot plasmas in vacuum with electric discharge and then using early pulsed ruby lasers.

Lowering of stimulated Raman scattering threshold as a result of light capture

Stimulated Raman Scattering in globular photonic crystals and globular photonic glasses at different diameters of globules (250 – 400 nm) with embedded molecular liquids is studied under excitation by nanosecond or picoseconds laser pulses. Substantial decrease of Stimulated Raman Scattering threshold was observed. Such phenomenon was explained as the result of laser radiation field increase in globular photonic structures due to photonic density of states enhancement near the edges of photonic stop bands of photonic crystals and due to Mie resonance or whispering gallery modes effect revealing in photonic glasses. Stimulated Raman Scattering threshold lowering as a result of light capture in globular photonic crystals and photonic glasses opens the way to new efficient laser sources created on the base of composite globular photonic structures. Experimental data on spectra of Stimulated Raman Scattering in light and heavy waters are presented. As sources of exciting light the powerful ultra short solid state laser pulses with 532.0 nm wavelength and giant pulses of Ruby laser (694.3 nm) have been used. Several Stokes and anti-Stokes satellites were observed. Libration modes have been excited and resulted in some additional Raman bands at low frequency region and also as combining tones.

Spectroscopic Study and Motion Analysis of Arc Spot Initiated on Nanostructured Tungsten

Arcing on the nanostructured tungsten surface has been examined recently because it gives rise to the erosion of materials and impurity transport toward the core plasma in a nuclear fusion reactor. Arcing was initiated on a helium-exposed tungsten surface, on which nanostructured tungsten was formed, by irradiation with ruby laser pulses of 0.08 MJ·m-2. The motion of an arc spot was observed with a fast-framing camera. The magnetic field strength and arc current dependences of velocity were discussed on the basis of experimental observation. Arc trails were observed using a digital fine scope to determine the relationship between the grouping width of an arc trail and arc velocity; the changes in grouping width and condition of the specimen surface are discussed. Spectroscopic measurements were performed to determine the electron temperature by the Boltzmann plot method.

Photo ionisation in mass spectrometry: light, selectivity and molecular ions

This topical issue of the journal Analytical and Bioanalytical Chemistry (ABC) is devoted to Photo Ionisation in Mass Spectrometry. Some of the publications presented in this special issue are based on contributions to a full-day scientific lecture session entitled Light and Molecular Ions—Photo Ionisation in Mass Spectrometry organised in the framework of the 2012 Analytica Conference in Munich. All twenty-one publications, including this introductory editorial, focus on this topic. As guest editor I am happy to introduce you to the content of the issue. Approximately 40 years after the beginning of the now 100year-long history of mass spectrometry [1], photo ionisation was invented—the first photo ions being observed in the fifties of the last century [2–4]. Vacuum UV (VUV) lamps were used for single-photon ionisation (SPI) of gaseous analytes. An overview of the physical fundamentals of photo ionisation in the gas phase is available in the literature [5]. The generation of sufficiently intense light in the required photon energy band has always been a challenge, and sometimes still is. The discovery of the laser effect and the technological realisation of pulsed high-power lasers started a new era in photo ionisation. Nearly coincidentally with the invention of the laser, the first laser desorption/ionisation (LDI) mass spectrometric experiments were reported; in these, ruby laser pulses were used for formation of ions from different solid materials [6]. The first observation of laser-induced gasphase photo ionisation, by a process later named multi photon ionisation (MPI), was reported in 1970 [7]. Following this pioneering work, application of resonance-enhanced multi photon ionisation to mass spectral analysis of organic molecules was introduced in 1978 [8]. With the invention of the third harmonic generation (THG) gas cell setups for production of VUV laser pulses in 1973 [9], a laser-based VUV light source also became available for SPI mass spectrometry [10]. A large variety of widely used analytical methods and technologies evolved from these initial studies on ionisation by either photon–molecule or laser pulse–surface interactions. A schematic time-of-flight mass spectrometer and some photo ionisation (PI) techniques used in analytical mass spectrometry are depicted in Fig. 1. Other PI techniques are given as acronyms only, and there is no claim to completeness. Onemeasure of the acceptance and applicability of scientific methods and technology is the annual number of publications, as recorded by, e.g., the ISI Web of Knowledge/Science. Figure 2 shows the development of the “photo ionisation mass spectrometry” field, measured by use of this bibliographical tool in the time range 1996–2012. It is obvious that laserdesorption-based techniques are by far the most commonly used. Laser desorption/ionisation (LDI), laser ablation (LA), and laser desorption (LD) and, in particular, matrix-assisted laser desorption/ionisation (MALDI) in conjunction with mass spectrometry dominate the numbers of applications, stimulated by the readily applicability ofMALDImass spectrometry to the life sciences (lipids, proteomics etc.). However, the intention of this special issue is to show the variety of methods and approaches of photo ionisation-based techniques. Although the most dominant application of PIMS, MALDI-MS [11] is already covered by a very large variety of monographs and books. Therefore, only a limited number of articles on MALDI are included in this special issue. These articles cover an important fundamental Published in the topical collection Photo Ionisation in Mass Spectrometry with guest editor Ralf Zimmermann.

Experimental observation of stimulated low-frequency Raman scattering in water suspensions of silver and gold nanoparticles

In this Letter we report on experimental observation of stimulated low-frequency Raman scattering (SLFRS) in gold and silver nanoparticle suspensions excited by 20 ns ruby laser pulses, SLFRS propagated in forward and backward directions with a maximum conversion efficiency up to 20%. Frequency shift for silver nanoparticle suspension was found to be 0.33 THz and for gold nanoparticle suspension 0.435 THz. This type of stimulated scattering of light can be used as an effective source of biharmonic pumping for solving a large number of practical tasks.

Artistic Representation with Pulsed Holography

This thesis describes artistic representation through pulsed holography. One of the prevalent practical problems in making holograms is object movement. Any movement of the object or film, including movement caused by acoustic vibration, has the same fatal results. One way of reducing the chance of movement is by ensuring that the exposure is very quick; using a pulsed laser can fulfill this objective.The attractiveness of using pulsed laser is based on the variety of materials or objects that can be recorded (e.g., liquid material or instantaneous scene of a moving object). One of the most interesting points about pulsed holograms is that some reconstructed images present us with completely different views of the real world. For example, the holographic image of liquid material does not appear fluid; it looks like a piece of hard glass that would produce a sharp sound upon tapping. In everyday life, we are unfamiliar with such an instantaneous scene.On the other hand, soft-textured materials such as a feather or wool differ from liquids when observed through holography. Using a pulsed hologram, we can sense the soft touch of the object or material with the help of realistic three-dimensional (3-D) images. The images allow us to realize the sense of touch in a way that resembles touching real objects.I had the opportunity to use a pulsed ruby laser soon after I started to work in the field of holography in 1979. Since then, I have made pulsed holograms of activities, including pouring water, breaking eggs, blowing soap bubbles, and scattering feathers and popcorn. I have also created holographic art with materials and objects, such as silk fiber, fabric, balloons, glass, flowers, and even the human body. Whenever I create art, I like to present the spectator with a new experience in perception. Therefore, I would like to introduce my experimental artwork through those pulsed holograms.

Effects of pressure characteristics on transfection efficiency in laser-induced stress wave-mediated gene delivery

Laser-induced stress waves (LISWs) generated by irradiating a light-absorbing medium with a pulsed laser can transiently increase the permeability of cell membranes for gene delivery. In this study, we investigated the effects of pressure characteristics of LISWs upon gene transfection efficiency using lasers with different pulse durations: a 6-ns pulsed Nd:YAG laser and 20-ns and 200-µs pulsed ruby lasers. LISWs were generated by irradiating a black rubber disk, on which a transparent plastic sheet was adhered for confinement of the laser-produced plasma. Rat dorsal skin was injected with plasmid DNA coding for luciferase, to which LISWs were applied. With nanosecond laser pulses, transfection efficiency increased linearly with increasing positive peak pressure in the range of 35 to 145 MPa, the corresponding impulse ranging from 10 to 40 Pa⋅s. With 200-µs laser pulses, on the other hand, efficient gene expression was observed by the application of LISWs even with a 10-fold-lower peak pressure (∼5 MPa), the corresponding impulse being as large as 430 Pa⋅s. These results indicate that even at low peak pressures, efficient transfection can be achieved by extending the pressure duration and hence by increasing the impulse of LISWs, while the averaged expression efficiencies were relatively low.