Effective Absorption Cross Section Research Articles

Synthesis and photophysical properties of doubly porphyrin-substituted cyanine dye

New porphyrin-(cyanine dye) composites, in which two porphyrins are bridged by a cyanine dye through triple bonds, were synthesized. In the UV-vis absorption spectra of the composites, the Soret band and Q-band were red-shifted to 436 and 575–640 nm, respectively. The absorption originating from the cyanine dye portion was also red-shifted from 710 nm to 764 nm, suggesting the expansion of πconjugation over the porphyrin and cyanine dye parts. Fluorescence studies suggested that energy transfer from the porphyrin portion to the cyanine dye moiety occurred. The fluorescence intensity decreased with increasing dielectric constants of solvents, suggesting intramolecular photoinduced electron transfer from the porphyrin to the cyanine dye parts. The effective two-photon absorption (2PA) cross-section values were measured using a nanosecond open aperture Z-scan method. The maximum effective 2PA cross-section and two-photon excited fluorescence cross-section values were 33,000 GM and 4,800 GM, respectively, at 860 nm in toluene/pyridine (95:5).

Measurement of Atmospheric Ozone by Cavity Ring-down Spectroscopy

Ozone plays a key role in both the Earth's radiative budget and photochemistry. Accurate, robust analytical techniques for measuring its atmospheric abundance are of critical importance. Cavity ring-down spectroscopy has been successfully used for sensitive and accurate measurements of many atmospheric species. However, this technique has not been used for atmospheric measurements of ozone, because the strongest ozone absorption bands occur in the ultraviolet spectral region, where Rayleigh and Mie scattering cause significant cavity losses and dielectric mirror reflectivities are limited. Here, we describe a compact instrument that measures O3 by chemical conversion to NO2 in excess NO, with subsequent detection by cavity ring-down spectroscopy. This method provides a simple, accurate, and high-precision measurement of atmospheric ozone. The instrument consists of two channels. The sum of NO2 and converted O3 (defined as Ox) is measured in the first channel, while NO2 alone is measured in the second channel. NO2 is directly detected in each channel by cavity ring-down spectroscopy with a laser diode light source at 404 nm. The limit of detection for O3 is 26 pptv (2 sigma precision) at 1 s time resolution. The accuracy of the measurement is ±2.2%, with the largest uncertainty being the effective NO2 absorption cross-section. The linear dynamic range of the instrument has been verified from the detection limit to above 200 ppbv (r2>99.99%). The observed precision on signal (2 sigma) with 41 ppbv O3 is 130 pptv in 1 s. Comparison of this instrument to UV absorbance instruments for ambient O3 concentrations shows linear agreement (r2=99.1%) with slope of 1.012±0.002.

Quantification of Iron (Fe) in Lithium Niobate by Optical Absorption

A quantitative method, based solely on optical absorption, to determine the total iron (Fe) concentration in Fe : LiNbO3 is proposed. Absorption spectra of several samples doped by thermal diffusion with different concentrations and different [Fe2+]/[Fe3+] ratios show an isosbestic point at 342 nm. At this wavelength the absorption is proportional to the total Fe concentration and does not depend on the oxidation state. Thanks to the large number of samples covering a wide range of concentrations, in this work it was possible to estimate an effective absorption cross-section relating the absorbance of a given sample to its iron content. The main advantage of the proposed method is in its simplicity and the fact that the result does not depend on the reduction degree of the sample. As it is known that the absorbance of Fe : LN at another wavelength (532 nm) gives information on the amount of Fe2+ present in the sample, our method makes it possible to characterize both the total Fe amount and its reduction degree within a single optical absorption measurement.

Color tunability with temperature and pump intensity in Yb3+/Tm3+ codoped aluminosilicate glass under anti-Stokes excitation

Pump and thermally induced color tunabilities were demonstrated in Yb(3+)/Tm(3+) codoped low silica calcium aluminosilicate (LSCAS) glass under anti-Stokes excitation at 1.064 microm. The effects of pump intensity and sample's temperature on the upconversion emissions and mainly on the color tunabilities (from 800 to 480 nm) were investigated. The results revealed a 20- and a threefold reductions at 800/480 nm ratio as, respectively, the pump intensity and sample's temperature were increased from 27 to 700 kW/cm(2) and from 296 to 577 K. These behaviors with pump intensity and temperature (a strong increase of the 480 nm emission in comparison with the 800 nm one) were attributed to the several efficient processes occurring in the LSCAS system (Yb(3+)-->Tm(3+) energy-transfer processes, easy saturations of the Yb(3+) and Tm(3+) excited states, and radiative emissions). Besides these assigns, the temperature dependence is mainly assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. Theoretical analyses and fits of the experimental data provided quantitative information.

Absolute Measurements of Total Peroxy Nitrate Mixing Ratios by Thermal Dissociation Blue Diode Laser Cavity Ring-Down Spectroscopy

Peroxycarboxylic nitric anhydrides (PANs) have long been recognized as important trace gas constituents of the troposphere. Here, we describe a blue diode laser thermal dissociation cavity ring-down spectrometer for rapid and absolute measurements of total peroxyacyl nitrate (SigmaPAN) abundances at ambient concentration levels. The PANs are thermally dissociated and detected as NO2, whose mixing ratios are quantified by optical absorption at 405 nm relative to a reference channel kept at ambient temperature. The effective NO2 absorption cross-section at the diode laser emission wavelength was measured to be 6.1 x 10(-19) cm2 molecule(-1), in excellent agreement with a prediction based on a projection of a high-resolution literature absorption spectrum onto the laser line width. The performance, i.e., accuracy and precision of measurement and matrix effects, of the new 405 nm thermal dissociation cavity ring-down spectrometer was evaluated and compared to that of a 532 nm thermal dissociation cavity ring-down spectrometer using laboratory-generated air samples. The new 405 nm spectrometer was considerably more sensitive and compact than the previously constructed version. The key advantage of laser thermal dissociation cavity ring-down spectroscopy is that the measurement can be considered absolute and does not need to rely on external calibration.

A pulsed, optically-pumped rubidium laser at high pump intensity

A rubidium laser operating at 795 nm is optically pumped by a pulsed titanium sapphire laser to investigate the dynamics of Diode Pumped Alkali Lasers (DPALs). Linear scaling of output intensity for longitudinal excitation at intensities of 1.3–43 kW/cm 2 and as much as 32 times threshold is observed. The slope efficiency depends directly on the number of absorbed photons for alkali concentrations of 0.8–2.0 × 10 13 atoms/cm 3 with no evidence for second order kinetics. The effective absorption cross section is reduced in part by the broad spectral width of the pump source relative to the pressure broadened lineshape. Spin orbit relaxation between the pumped and upper laser levels is sufficiently fast at 550 Torr of methane to prevent bottlenecking at all but the highest intensities. Comparison of laser characteristics with a quasi-two level analytic model suggests performance near the ideal steady-state limit, with the exception of modest mode matching.

Time resolved studies on pulsed fluorocarbon plasmas using chirped quantum cascade lasers

The kinetics of stable species has been studied in situ in pulsed CF4/H2 radio frequency discharges by means of time resolved quantum cascade laser absorption spectroscopy. The absorption spectra were usually recorded with a time resolution of 5 ms and required a multi-species analysis, because of interfering complex absorption features of CF4 and C3F8. For this reason, measurements were carried out at two different spectral positions. High resolution spectroscopic data were established by calibrating effective absorption cross sections and their relative temperature dependences for the relevant low pressure conditions (10 Pa). During the discharge a decrease in the CF4 density by ∼12% was observed. The off-phase was characterized mainly by the gas exchange. The C3F8 density in the off-phase was found to be of the order of the detection limit (3 × 1013 cm−3). Spectra acquired during the plasma-on phase showed a rapid temperature-induced increase in the absorption signal and, additionally, suggested the influence of a short-lived broadband absorbing species. The reasonable assumption of the presence of CF4 hotbands has not yet enabled a further quantification.

60]Fullerene metal complexes with large effective two-photon absorption cross-section

Fourteen novel complexes of fullerene C(60) with metal dialkyldithiophosphate, {[(RO)(2)PS(2)](2)M}·2C(60) (R = Me and Et; M = Mn, Fe, Co, Ni, Cu, Zn and Pd), can be obtained in high yield by the reaction of metal(II) dialkyldithiophosphate complexes with C(60) fullerene. Their structures are determined by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis, FT-IR and UV-vis, and are supplied by single crystal X-ray data. The compound {[(EtO)(2)PS(2)](2)Pd}·2C(60) was also studied by the HRTEM image and SAED patterns. Studies of the optical properties of the complexes of fullerene C(60) with metal dialkyldithiophosphate show that these compounds all have very strong nonlinear optical absorption effects. The nonlinear absorption of fourteen complexes of fullerene C(60) with metal dialkyldithiophosphate (in o-dichlorobenzene and in the solid state) was measured by the open-aperture Z-scan technique at a wavelength of 532 nm. DFT calculations are also used to discuss the stability of these complexes and to confirm the structural assignments.

Quantum dot infrared photodetector enhanced by surface plasma wave excitation

Up to a thirty-fold detectivity enhancement is achieved for an InAs quantum dot infrared photodetector (QDIP) by the excitation of surface plasma waves (SPWs) using a metal photonic crystal (MPC) integrated on top of the detector absorption region. The MPC is a 100 nm-thick gold film perforated with a 3.6 microm period square array of circular holes. A bare QDIP shows a bias-tunable broadband response from approximately 6 to 10 microm associated with the quantum confined Stark (QCS) effect. On the other hand, an MPC-integrated QDIP exhibits a dominant peak at 11.3 microm with a approximately 1 microm full width at half maximum and the highly enhanced detectivity at the bias polarity optimized for long wavelength. This is very different from the photoresponse of the bare QDIP but fully consistent with the direct coupling of the QDs in the detector absorption region to the SPWs excited at the MPC/detector interface by incident photons. The SPW resonance wavelength, lambda, for the smallest coupling wavevector of the array in the MPC is close to 11.3 microm. The response also shows other SPW-coupled peaks: a significant peak at 8.1 microm (approximately lambda/radical2) and noticeable peaks at 5.8 microm (approximately lambda/2) and 5.4 microm (approximately lambda/ radical5) which correspond to higher-order coupling wavevectors. For the opposite bias, the MPC-integrated QDIP shows the highest response at 8.1 microm, providing a dramatic voltage tunability that is associated with QCS effect. SPWs propagate with TM (x, z) polarization along the MPC/detector interface. The enhanced detectivity is explained by these characteristics which increase both the effective absorption cross section with propagation and the interaction strength with TM polarization in the coupling to the QDs. Simulations show good qualitative agreement with the observed spectral behavior.

Comparing electron transport with gas exchange: parameterising exchange rates between alternative photosynthetic currencies for eukaryotic phytoplankton

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 56:147-162 (2009) - DOI: https://doi.org/10.3354/ame01303 AME Special: 'Progress and perspectives in aquatic primary productivity: highlights of the GAP VIII workshop, Eilat, Israel, 2008' Comparing electron transport with gas exchange: parameterising exchange rates between alternative photosynthetic currencies for eukaryotic phytoplankton David J. Suggett1,*, Hugh L. MacIntyre2, Todd M. Kana3, Richard J. Geider1 1Department of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK 2Dauphin Island Sea Lab, 101B Bienville Blvd, Dauphin Island, Alabama 36528, USA 3Horn Point Laboratory, 2020 Horns Point Rd, Cambridge, Maryland 21613, USA *Email: dsuggett@essex.ac.uk ABSTRACT: Estimates of aquatic primary productivity derived from in situ active chl a fluorescence have rapidly gained popularity over the past 2 decades. This trend has been driven primarily by the need to improve upon ‘conventional’ carbon (C) uptake- or oxygen (O2) evolution-based productivity estimates that require water samples to be incubated ex situ. Unlike the conventional approaches to measuring productivity, chlorophyll fluorescence measurements inherently describe only the activity of photosystem II (PSII) in the light reactions; thus, the photosynthetic ‘currency’ of the fluorescence-based approach is an electron turnover rate for PSII (ETRPSII). A photosynthetic currency of electrons has limited ecological relevance but can be converted to a currency of carbon if an ‘exchange rate’, i.e. a value or factor of equivalence for any single time point, is applied. We used fast repetition rate fluorometry (FRRf), mass inlet membrane spectrometry (MIMS) and 14C uptake to determine ETRPSII, gross and net O2 evolution and C fixation measured simultaneously for 6 microalgal species and for different steady-state growth conditions. Quantifying the PSII reaction centre (RCII) concentration and the spectral dependency of the effective absorption cross section yielded an FRRf approach that provided a robust estimate of the ETRPSII and gross O2 evolution for all species and conditions tested; however, the ETRPSII exceeded carbon dioxide (CO2) uptake by a factor of ~5.4 to 11.6. At least 3 species exhibited substantial light-dependent O2 cycling to account for ~40 to 60% of the difference between the ETRPSII and CO2 uptake. The highly variable nature of the ETRPSII:CO2 uptake ‘exchange rate’ observed here highlights the need for future studies that rely on active fluorescence to examine aquatic productivity to focus towards a systematic description of how electrons are coupled to C fixation in nature. KEY WORDS: Fast repetition rate fluorescence · Electron transport · Photosynthesis · Oxygen evolution · Carbon uptake · Phytoplankton Full text in pdf format PreviousNextCite this article as: Suggett DJ, MacIntyre HL, Kana TM, Geider RJ (2009) Comparing electron transport with gas exchange: parameterising exchange rates between alternative photosynthetic currencies for eukaryotic phytoplankton. Aquat Microb Ecol 56:147-162. https://doi.org/10.3354/ame01303 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 56, No. 2-3. Online publication date: September 03, 2009 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2009 Inter-Research.

Studies on third-order nonlinear optical properties and reverse saturable absorption in polythiophene/poly (methylmethacrylate) composites

We report here the studies on third-order nonlinear optical properties of two novel polythiophene composite films investigated using the Z-scan technique. The measurements were carried out using a Q-switched, frequency doubled Nd:YAG laser producing 7 nanosecond laser pulses at 532 nm. Z-scan results reveal that the composite films exhibit self-defocusing nonlinearity. The real and imaginary parts of the third-order nonlinear optical susceptibility were of the order 10−12 esu. The effective excited-state absorption cross section was found to be larger than the ground state absorption cross section, indicating that the operating nonlinear mechanism is reverse saturable absorption (RSA). The polythiophene composite films also exhibit good optical power limiting of the nanosecond laser pulses. The nonlinear optical parameters are found to increase on increasing the strength of the electron-donor group, indicating the dependence of χ (3) on the electron-donor/acceptor units of polythiophenes.

Rare-earth doped solid-state phosphor with temperature induced variable chromaticity

Temperature induced variable chromaticity lanthanide multidoped solid-state phosphors are presented. The phosphors are composed of ytterbium-sensitized multiple-doped (Tm, Er, Ho) PbGeO 3–PbF 2–CdF 2 glass excited at 1.064 µm. The temperature induced color variation exploits the heat enhanced effective absorption cross-section of the ytterbium sensitizer under quasi-resonance excitation. The temperature enhancement of the energy-transfer mechanism between the sensitizer and the appropriate active light emitter allows the selective intensity control of the RGB emissions due to distinct excitation routes. The suitable combination of active ions generated variable chromaticity light with CIE-1931 coordinates changing from CIE- X = 0.283; Y = 0.288 at 20 °C to CIE- X = 0.349;Y = 0.412 at 190 °C, and CIE- X = 0.285; Y = 0.361 at 25 °C to CIE- X = 0.367; Y = 0.434 at 180 °C in Yb 3+/Tm 3+/Ho 3+ and Yb 3+/Tm 3+/Er 3+ samples, respectively.

The third-order nonlinear optical properties of novel styryl dyes

The third-order nonlinear optical properties of two novel styryl dyes, namely, 1,3-diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1 H,5 H)-dione and 5-(3,4-dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1 H,5 H)-dione were studied using the Z-scan technique employing 7 ns laser pulses at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, magnitude of effective third-order susceptibility and coupling factor were determined. The optical power limiting behavior of the colorants was ascribed to two-photon absorption phenomenon. Nonlinear absorption cross-section increased with increase in π electron density and the effective two-photon absorption cross-section was two orders of magnitude larger than those of commercially available azo compounds. The results suggest that these colorants offer promise as nonlinear optical materials for device applications.

Long lifetime and efficient emission from Er 3+ ions coupled to Si nanoclusters in Si-rich SiO 2 layers

Reactive magnetron co-sputtering of two confocal SiO 2 and Er 2O 3 cathodes in argon–hydrogen plasma was used to deposit Er-doped Si-rich SiO 2 layers. The effects of the deposition conditions (such as RF power applied on each cathode and total plasma pressure) and annealing treatment (temperature and duration) on structural, compositional and photoluminescence (PL) properties of the layers were examined. It was found that a significant enhancement of both Er 3+ PL intensity and emission lifetime up to 9 ms have been reached through monitoring of the conditions of both deposition process and annealing treatment. The effective absorption cross section and the fraction of Er ions coupled to Si clusters were analyzed. It was shown an increase of the fraction of Er 3+ ions coupled to Si up to 11%.

Application of quantum cascade laser absorption spectroscopy to studies of fluorocarbon molecules

The recent advent of quantum cascade lasers (QCLs) enables room-temperature mid-infrared spectrometer operation which is particularly favourable for industrial process monitoring and control, i.e. the detection of transient and stable molecular species. Conversely, fluorocarbon containing radio-frequency discharges are of special interest for plasma etching and deposition as well as for fundamental studies on gas phase and plasma surface reactions. The application of QCL absorption spectroscopy to such low pressure plasmas is typically hampered by non-linear effects connected with the pulsed mode of the lasers. Nevertheless, adequate calibration can eliminate such effects, especially in the case of complex spectra where single line parameters are not available. In order to facilitate measurements in fluorocarbon plasmas, studies on complex spectra of CF4 and C3F8 at 7.86 μm (1269 – 1275 cm-1) under low pressure conditions have been performed. The intra-pulse mode, i.e. pulses of up to 300 ns, was applied yielding highly resolved spectral scans of ∼ 1 cm-1 coverage. Effective absorption cross sections were determined and their temperature dependence was studied in the relevant range up to 400 K and found to be non-negligible.

Interpretation of fast repetition rate (FRR) fluorescence: signatures of phytoplankton community structure versus physiological state

Introduction of active chlorophyll a fluo- rescence protocols, in particular fast repetition rate (FRR) fluorometry, to oceanography and limnology 15 yr ago has enabled rapid assessment of photosyn- thetic physiology in situ. The FRR protocol generates simultaneous measurements of Photosystem II (PSII) effective absorption cross sections (termed σPSII) and photochemical efficiency (termed Fv/Fm). Both Fv/Fm and σPSII measurements have been utilised to examine the effects of physiological stress on the photosynthetic apparatus of phytoplankton in an ever growing num- ber of fluorescence-based studies. However, it is now becoming clearer that in situ values of Fv/Fm and σPSII also contain taxonomic information. Here, we present

Bisporphyrin connected by tetrathiafulvalene

A new porphyrintetrathiafulvalene composite, where two porphyrins are bridged by te trathiafulvalene (TTF) using acetylene bonds was synthesized. The Q-band of the monomeric porphyrin appears at 590 nm whereas that of the composite is red-shifted to 620 nm and intensified. The Soret band is also red-shifted from 427 nm to 435 nm and much broadened, indicating the expansion of π-conjugation over the porphyrin and tetrathiafulvalene units. The HOMOs and LUMOs were calculated using time-dependent density functional theory. Voltammetric experiments revealed that the first oxidation potential of the TTF moiety in the composite was shifted by +155 mV compa red with TTF in the absence of composite. The effective two-photon absorption (2PA) cross section values were measured by using a nanosecond open aperture Z-scan method. The maximum effective 2PA cross section values were obtained at 760 nm, as 7300 GM in benzonitrile and 5900 GM in toluene. The values obtained in the polar solvent were 1.2 to 1.5 times larger than those in the nonpolar solvent.

A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO(2) (versus a laser broadband cavity ringdown spectrometer) and for H(2)O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+delta absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO(3) as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1sigma detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument's performance under field work conditions is presented, in this case of measurements of the sum of NO(3)+N(2)O(5) concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign.

Distribution of bacteriochlorophyll between the pigment-protein complexes of the sulfur photosynthetic bacterium Allochromatium minutissimum depending on light intensity at different temperatures

Variation of the distribution of bacteriochlorophyll a (BChl a) between external antenna (LH2) and core complexes (LHl + RC) of the photosynthetic membrane of the sulfur bacterium Allochromatium minutissimum was studied at light intensities of 5 and 90 Wt/m2 in the temperature range of 12-43 degrees C. The increase of light intensity was shown to result in a 1.5- to 2-times increase of a photosynthetic unit (PSU). PSU sizes pass through a maximum depending on growth temperature, and the increase of light intensity (5 and 90 Wt/m2) results in a shift of the maximal PSU size to higher temperatures (15 and 20 degrees C, respectively). In the narrow temperature interval of approximately 14-17 degrees C, the ratio of light intensity to PSU size is typical of phototrophs: lower light intensity corresponds to larger PSU size. The pattern of PSU size change depending on light intensity was shown to differ at extreme growth temperatures (12 degrees C and over 35 degrees C). The comparison of Alc. minutissimum PSU size with the data on Rhodobacter capsulatus and Rhodopseudomonas palustris by measuring the effective optical absorption cross-section for the reaction of photoinhibition of respiration shows a two to four times greater size of light-harvesting antenna for Alc. minutissimum, which seems to correspond to the maximum possible limit for purple bacteria.

Segregation during crystal growth from melt and absorption cross section determination by optical absorption method

Segregation during crystal growth from melt under two conditions is studied by using crystal mass, which can be measured easily, as an independent variable, and a method to determine the effective segregation coefficient and absorption cross section of optical dopant is given. When the segregated solute disperses into the whole or just a part of melt homogenously, the concentration Cs in solid interface will change by different formulas. If the crystal growth interface is conical and segregated solute disperses into melt in total or part, the solute concentration at r = 2/3R, where r is the distance from the growth cross section center and R the crystal radius, is independent on the shape of the crystal growth interface, and its variation at r = 2/3R can be regarded as the result from crystal growth in flat interface. With Cs variation formula in solid and absorption cross section σ for optical dopant, the absorption coefficients along the crystal growth direction can be calculated, and the corresponding experimental value can be obtained through the crystal optical absorption spectra. By minimizing the half sum, whose independent variables are k, ΔW or σ, of the difference square between the calculated and experimental absorption coefficients from one or more absorption peaks along the crystal growth direction, k and σ, or k and ΔW, can be determined at the same time through the Levenberg-Marquardt iteration method. Finally, the effective segregation coefficient k, ΔW and absorption cross sections of Nd:GGG were determined, the results fitted by two formula gave more closed effective segregation coefficient, and the value ΔW also indicates that the segregated dopant had nearly dispersed into the whole melt. Experimental results show that the method to determine effective segregation coefficient k, ΔW and absorption cross sections σ is convenient and reliable, and the two segregation formulas can describe the segregation during the crystal growth from melt relatively commendably.