共查询到20条相似文献,搜索用时 31 毫秒
1.
Laser dyes which are commonly used in pulsed laser pumped dye laser (PLPDL) systems have been investigated. It is shown that photoquenching plays an important role in the pumping process of all laser dyes, determining the efficiency of the PLPDL. Molecular parameters, such as absorption cross sections at various pumping wavelengths and fluorescence lifetimes of theS
n
(n>1) excited electronic states of laser dyes, have been determined utilizing the photoquenching technique. 相似文献
2.
Near-infrared dyes as contrast-enhancing agents for spectroscopic optical coherence tomography 总被引:2,自引:0,他引:2
Optical coherence tomography (OCT) images of biological tissues often have low contrast. Spectroscopic optical coherence tomography (SOCT) methods have been developed to enhance contrast but remain limited because most tissues are not spectrally active in the frequency bands of laser sources commonly used in OCT. Near-infrared (NIR) dyes with absorption spectra features within the OCT source spectrum can be used for enhancing contrast in this situation. We introduce and demonstrate the use of NIR dyes as contrast agents for SOCT. Contrast-enhanced images are compared with fluorescence microscopy, demonstrating a link between SOCT and fluorescence imaging. 相似文献
3.
S. Sinha A.K. Ray S. Kundu S. Sasikumar K. Dasgupta 《Applied physics. B, Lasers and optics》2002,75(1):85-90
Photophysical properties of heavy-water-based rhodamine dye solutions have been investigated, with a view to assess the suitability
of heavy water as a solvent for high-power, high-repetition-rate dye lasers and amplifiers. We have measured the quantum yield
of fluorescence of the commonly used dyes rhodamine-6G, rhodamine-B and kiton-red, dissolved in heavy water, ethanol and normal
water. The performance of a heavy-water-based pulsed rhodamine-6G dye laser has been investigated in broadband, as well as
in narrowband wavelength-tunable resonator configurations, yielding laser efficiencies comparable to those achieved with ethanolic
solutions of the same dye. We have also studied the thermo-optic properties of normal and heavy water, using the Z-scan technique.
Finally, photodegradation rates for laser dyes have been compared in heavy water, normal water and ethanol. Our results establish
heavy water as a solvent superior to both ethanol and normal water, on account of the lower thermo-optic effects and the higher
photostability of rhodamine dyes when dissolved in heavy water.
Received: 8 February 2002 / Published online: 8 August 2002 相似文献
4.
A. N. Fletcher R. A. Hollins R. F. Kubin R. A. Henry T. M. AtienzaMoore M. E. Pietrak 《Applied physics. B, Lasers and optics》1983,30(4):195-202
Solutions of 13 fluorescent dyes have been used as energy transfer agents in place of the normal coolant of a Nd-YAG laser. Dye mixtures were used in a few cases where incomplete absorption of flashlamp pump energy was observed. Improvements of over 100% in laser output were observed for some dyes having a long Stokes shift when tested at both a low-input energy and a low-pulse rate. However, the absolute improvement in laser output for these dye solutions was small, and the improvement could be obtained almost as well by merely increasing the pulse rate. Various factors associated with the effectiveness of transfer-dye solutions are discussed. 相似文献
5.
6.
K. K. Jagtap D. K. Maity A. K. Ray K. Dasgupta S. K. Ghosh 《Applied physics. B, Lasers and optics》2011,103(4):917-924
A combined experimental and theoretical study of the photo-physical, laser properties and molecular structures of three relatively
recent Pyrromethene (PM) class dyes, PM597, PM580 and PM567, have been carried out. Laser characteristics of these three PM
dyes were compared with three other widely used Rhodamine (RH) class dyes, RH6G, RHB and KRS, using a narrow-band dye laser
setup, transversely pumped by the second harmonic (532 nm) of a Q-switched Nd-YAG laser. In addition to generating comparative
data of these dyes for optimal use in dye lasers, we observed that unlike the RH dyes, the PM dyes show high efficiencies
and wide tunability, despite the low fluorescence yield and high rate of non-radiative decay. Particularly, PM597 dye, in
spite of a very low quantum yield of fluorescence (Φ=0.42), high non-radiative decay rate, and a large distortion from planarity
in its excited state, when used in a laser cavity it exhibited similar laser efficiency and a beneficially wider tuning curve
in comparison to other two PM dyes. Theoretical studies were carried out applying density functional theory and time-dependent
density functional theory (DFT/TDDFT) to obtain new information on ground and the first excited state geometrical parameters
of the PM dyes. Good correlation between calculated molecular properties and experimental results was observed for the evolution
of the longest wavelength absorption maximum. 相似文献
7.
Mahmoud A. S. Sakr Sayed A. Abdel Gawad Maram T. H. Abou Kana El-Zeiny M. Ebeid 《Journal of fluorescence》2017,27(4):1267-1275
This article reports the optical properties such as absorption profile, molar absorptivity, fluorescence profile and photo-physical parameters such as dipole moment, oscillator strength, fluorescence quantum yields, fluorescence lifetimes, laser performance and finally photostability of 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBOT),1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOB), 5-diphenyel-oxazole (PPO) laser dyes in different restricted hosts. (BBOT), (POPOB) and (PPO) are embedded in transparent silica-based nanoporous sol-gel glass and copolymer matrix of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). The absorption and fluorescence properties of these laser dyes in sol-gel glass matrices are compared with their respective properties in copolymer host. In case of sol-gel matrix, all dyes had higher quantum yields as well as lasing wavelength maxima. The laser performances as well as the photostability of these laser dyes in sol-gel glass displayed senior behavior compared with (MMA/ HEMA) copolymer samples upon using nitrogen laser (337.1 nm) as pumping energy. 相似文献
8.
R.Justin RajeshPrem B Bisht 《Journal of luminescence》2002,99(3):301-309
Laser-induced transient grating technique has been used to measure the diffraction efficiency (η) and calculate the third-order nonlinear susceptibility (χ(3)) of some laser dyes. Theoretical simulations have been carried out on η and χ(3) as a function of wavelength covering the spectral range corresponding to the first excited singlet state of the dyes. Theoretically simulated values have been found in agreement to those observed experimentally. The decay profiles for these dyes have been measured by using diffraction of a delayed probe laser pulse to estimate the relaxation times in the excited state. 相似文献
9.
10.
Photoacoustic spectra of rhodamine 110, rhodamine 6 G, rhodamine B, rhodamine 101 and coumarin 102 laser dyes have been recorded
at room temperature of 25°C in the spectral range of 350–750 nm. These samples were taken in powder as well as in solution
forms. For this purpose the closed and the open photoacoustic cells have been used. It is hoped the present study would be
useful for characterization of these dyes. 相似文献
11.
分子轨道法计算三苯二恶嗪类分子的电子光谱 总被引:1,自引:0,他引:1
王学杰 《光谱学与光谱分析》2002,22(1):9-11
采用改进的半经验分子轨道法 (PPP SCF MO)计算了 15种三苯二恶嗪类染料分子的电子结构和电子光谱 ,计算得到的最大吸收峰波长与实验值较好的一致 ,计算得到的荧光跃迁能 ΔEfl 与荧光峰波数νfl 存在如下关系 :νfl =11 6 837ΔEfl+3 34 85 (k·cm- 1 ) ,r=0 95 47,并讨论了电子结构与光谱性能的关系。 相似文献
12.
Results from experiments in which the ultraviolet pulses from a nitrogen laser are used to obtain laser action from organic dyes are described. The dyes include three in the xanthene group (rhodamine 6G, B, and sodium fluorescein) and two coumarins, 7-diethylamino-4-methylcoumarin and 7-N-dimethylamino-4, 6-dimethylcoumarin) in ethanol solvent. With these dyes, laser power is available over the entire visible range from 4200 to 6300 Å when used with a rotatabie diffraction grating. The range of tunability of one of the dyes was extended to 1000 Å by appropriate acidification. The spectral halfwidth of the light varied between 7 and 15 Å over the range of tunability. Maximum repetition rates of 100 pps were obtained. Maximum power efficiency of 25% was found for rhodamine 6G. Overall output pulse shapes were found to be in agreement with the theory of Sorokinet al. Output pulse widths varied from 1 to 7 nsec. Other dyes which we have found to lase by this method of excitation include acridone, chloro-aluminium pthalocyanine and 4-methylumbelliferone. However, these dyes will not be discussed further in the text.Partially supported by US Army Research Office, Durham, North Carolina. 相似文献
13.
Sina Brockmann Thuro Arnold Bernd Schweder Gert Bernhard 《Journal of fluorescence》2010,20(4):943-951
Bacteria in acidophilic biofilm communities, i.e. acid streamers and snottites, obtained from a subsurface mine in Königstein were visualized by fluorescence microscopy using four new fluorescent dyes (DY-601XL, V07-04118, V07-04146, DY-613). The pH of the bulk solution in which these bacteria thrive was pH 2.6 to 2.9. The new fluorescent dyes were all able to clearly stain and microscopically visualize in-situ the bacteria within the biofilm community without changing pH or background ion concentration. The commonly used fluorescent dyes DAPI and SYTO 59 were also applied for comparison. Both dyes, however, were not able to visualize any bacteria in-situ, since they were not stable under the very acid conditions. In addition, dye V07-04118 and dye DY-613 also possess the ability to stain larger cells which were presumably eukaryotic origin and may be attributed to yeast cells or amoeba-like cells. PCR analyses have shown that the dominant bacterial species in these acidophilic biofilm communities was a gram negative bacterium of the species Ferrovum myxofaciens. The presented four new dyes are ideal for in-situ investigations of microorganisms occurring in very acid conditions, e.g. in acidophilic biofilm communities when in parallel information on pH sensitive incorporated fluorescent heavy metals should be acquired. 相似文献
14.
Zuguang YAO Zhonghua ZHUBesearch Znstitats of Fine Chemicals of the East China University of Ohemical Technology Shanghai ChinaLvn YE Xiangchun YANG Shanghai Institute of Optics Fine Mechanics Academia Sinica Shanghai China 《Chinese Journal of Lasers》1992,1(1):17-21
In this paper, the characteristics of three novel near infrared laser dyes withwide-tuning ranges and high conversion efficiency are reported. The tunable spectral regions ofthese dyes pumped by the second harmonic pulse(532nm)of Nd: YAG laser are from 700nmto 900nm with a conversion efficiency between 6.6% and 9.0%. The aborption spectraand fluorescence spectra of these dyes are also given. 相似文献
15.
Different types of eye-protection filters are examined with the emphasis being laid on the irradiation-dependent spectral transmittance. Most of the dyes used for polycarbonate laser filters show the effect of induced transmittance. This may be critical with respect to eye safety because these absorber types are frequently used in filters for protection against alexandrite laser irradiation. 相似文献
16.
We report the development of a new series of laser dyes and describe the performance of these materials. This work was spurred by the realization that few laser dyes have an optimally shaped fluorescence emission for lasing action. Most of the dipole strength of the transition is concentrated in the 0.0 band, where lasing cannot occur, and very little is concentrated in the vibrational satellites 0–1 and 0–2 where lasing is possible. The new dyes are unsymmetrical materials which may be considered as a hybrid of a rhodamine molecule and a fluorescein molecule (fig. 1), and we consider them to be cyclized merocyanines. One dye in particular, 6-dimethylamino-9-o-carboxyphenylxanthen-3H-one (labelled SNH-8), has given power output and time stability better than the preferred lasing dye Rhodamine 6G. The effects of dye structure and of acid-base transitions on lasing activity will be discussed briefly. The theory of band-shaping and the detailed optical parameters of the new dyes will be presented separately. 相似文献
17.
S. Sinha S. Sasikumar A.K. Ray K. Dasgupta 《Applied physics. B, Lasers and optics》2007,87(1):145-149
Nonlinear refraction in various polymethyl methacrylate (PMMA) solid hosts when doped with fluorescent organic dyes, commonly
used as a laser active medium, has been studied. The observed thermal lensing effect arising from optical nonlinearity, results
from non-radiative energy transfer from the dye molecules to the solid matrix and is, therefore, strongly dependent on the
thermal properties and material parameters of the polymeric host. The non-linear index of refraction, n2, for each sample of dye doped polymeric host, has been measured employing the standard Z-scan technique. These measured values
of n2, have been used to determine the extent of variation in the index of refraction with varying temperature, dn/dT, for the
various host materials. Estimation of dn/dT is critical in determining the extent of thermal lensing in the dye doped solid-state
medium, that in turn determines the spatial quality and divergence of the generated laser beam delivered by a dye doped solid-state
laser system.
PACS 42.55.Mv; 42.65.Jx; 42.70.Jk 相似文献
18.
Fluorescence spectroscopy and imaging have been widely used for in vivo cancer diagnosis and therapy monitoring in preclinical models, as well as clinical translation. Great attempts have been made to develop novel fluorescence techniques and improve on existing ones, which can now be used in conjunction with newly developed fluorescent probes for specific cancer imaging. In this review, a broad overview of fluorescence techniques is provided, including photodynamic diagnosis, laser confocal endomicroscopy and fluorescence lifetime imaging, coupled with endogenous and exogenous fluorophores. In particular, endogenous fluorophores, such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), are highlighted as they are linked to cellular metabolism in precancer growth. The use of near‐infrared dyes, such as indocynanine green (ICG), for imaging deep‐tissue regions is also reviewed. In addition, diagnostic algorithms used for tissue classification and cancer detection will be discussed. Lastly, emerging technologies in fluorescence diagnosis will also be included. 相似文献
19.
Laser dyes Styryl-9 and Styryl-11 exhibit large tuning ranges of 780 to 900 nm respectively 770 to 850 nm with a lasing efficiency as high as 14% respectively 8% when pumped by all lines of the argon-ion laser, placing them among the most efficient and broadly tunable dyes known in the near-infrared wavelengths. Performance of these dyes is investigated for both cw standing wave and cw single-frequency travelling wave laser operation. 相似文献
20.
Results of an investigation of 19 organic dyes pumped by a 1.7 MW discharge-pumped XeCl excimer laser are reported. The dye-laser
emission covered a wide wavelength range from 340 nm to 710 nm.P-terphenyl shows efficient laser action. The highest energy conversion efficiency exceeds 40% in visible region. In comparison
with 250 kW nitrogen laser pumping, higher efficiencies are obtained for most of these dyes in the same dye-laser configuration. 相似文献