Lumbosacral Degenerative Stenosis in the Dog

A total of thirtyfive dogs with a Hansen type two disc protrusion of the lumbosacral region were operated upon with a technique consisting of dorsal decompression, dorsal anulectomy and disc curettage. The presurgical signs existed for 14 months (mean) and 97% of the animals had been treated unsuccessfully with antiinflammatory drugs. The mean age at the time of surgery was 7,2 years and the mean weight 28 kg. Seventyone percent of the animals were males. A postsurgical questionnaire was mailed to the owners – mean 30 months – after surgery. The results of the surgery were such that 69% of the owners reported that their dog ameliorated after surgery of which 53% found their dog to be completely cured. Comparing the surgical results of this group with a comparable group of animals operated with a dorsal decompression technique alone (without anulectomy), and of which the owners were questioned with the same questionnaire, yielded identical clinical results. Our conclusion therefore is, that the more aggressive and invasive surgery which is neither suitable nor appropriate in that subgroup of patients with lumbosacral degenerative stenosis, plus a type II Hansen disc protrusion and without any, neurological deficit.

The results of the surgical treatment of Hansen type II disc protrusion are described. Owners reported that 69% of the patients improved following the operation and that 53% were cured.

The dramatic development of X-ray photocrystallography over the past six decades

A short description of some of the paradigm-changing developments of the study of light-induced structural changes in molecular crystals is presented. The review is by no means comprehensive. The extensive literature on the subject should be consulted for further information.

Exploring the structural changes on excitation of a luminescent organic bromine-substituted complex by in-house time-resolved pump-probe diffraction

The structural changes accompanying the excitation of the luminescent dibromobenzene derivative, 1,4-dibromo-2,5-bis(octyloxy)benzene, have been measured by in-house monochromatic time-resolved (TR) diffraction at 90 K. Results show an increment of the very short intermolecular Br•••Br contact distance from 3.290 Å to 3.380 Å. Calculations show the Br…Br interaction to be strongly repulsive in both the Ground and Excited states but significantly relaxed by the lengthening of the contact distance on excitation. The stability of the crystals is attributed to the many weak C-H···Br and C-H···π intermolecular interactions. The study described is the first practical application of In-House Time-Resolved diffraction, made possible by the continuing increase in the brightness of X-ray sources and the sensitivity of our detectors.

A priori checking of the light-response and data quality before extended data collection in pump–probe photocrystallography experiments

In picosecond and slower pump–probe diffraction experiments, collection of response–ratio correlation sets prior to full data collection provides an invaluable confirmation of the existence of a light-induced signal prior to full data collection. If a response to light exposure is observed, the quality of the data being collected can be assessed. A number of such correlation plots both for synchrotron and in-house pump–probe data collection are presented.

Reply To: How Does Substitutional Doping Affect Visible Light Absorption in a Series of Homodisperse Ti11 Polyoxotitanate Nanoparticles--A Comment on the Band Gap Determination of the Fe(II) Cages

A summary of the evidence based on spectroscopy, calculated density of states (DOS) and photo-electrochemistry, for electron transfer from the occupied Fe(2+) (d)-β orbital located within the band gap of the [Ti4 O(OEt)15 (FeBr)] cluster, to its unoccupied Ti(d) orbitals is presented. The importance of the distinction between the concepts of band gap and HOMO-LUMO gap is emphasized.

Analysis of multicrystal pump-probe data sets. II. Scaling of ratio data sets

Two methods for scaling of multicrystal data collected in time-resolved photocrystallography experiments are discussed. The WLS method is based on a weighted least-squares refinement of laser-ON/laser-OFF intensity ratios. The other, previously applied, is based on the average absolute system response to light exposure. A more advanced application of these methods for scaling within a data set, necessary because of frequent anisotropy of light absorption in crystalline samples, is proposed. The methods are applied to recently collected synchrotron data on the tetra-nuclear compound Ag2Cu2L4 with L = 2-diphenylphosphino-3-methylindole. A statistical analysis of the weighted least-squares refinement residual terms is performed to test the importance of the scaling procedure.

A Theoretical Databank of Transferable Aspherical Atoms and Its Application to Electrostatic Interaction Energy Calculations of Macromolecules

A comprehensive version of the theoretical databank of transferable aspherical pseudoatoms is described, and its first application to protein-ligand interaction energies is discussed. The databank contains all atom types present in natural amino acid residues and other biologically relevant molecules. Each atom type results from averaging over a family of chemically unique pseudoatoms, taking into account both first and second neighbors. The spawning procedure is used to ensure that close transferability is obeyed. The databank is applied to the syntenin PDZ2 domain complexed with four-residue peptides and to the PDZ2 dimer. Analysis of the electrostatic interactions energies calculated by the exact-potential/multipole-moment-databank method stresses the importance of the P0 and P-2 residues of the peptide in establishing the interaction, whereas the P-1 residue is shown to play a much smaller role. Unexpectedly, the charged P-3 residue contributes significantly to the interaction. The class I and II peptides are bound with the same strength by the syntenin PDZ2 domain, though the electrostatic interaction energy of the P-2 residue is smaller for class I peptides. There is no difference between the interaction energies of the peptides with PDZ2 domains from single-domain protein fragments and those from PDZ1-PDZ2 tandems.

On the scaling of multicrystal data sets collected at high-intensity X-ray and electron sources

The need for data-scaling has become increasingly evident as time-resolved pump-probe photocrystallography is rapidly developing at high intensity X-ray sources. Several aspects of the scaling of data sets collected at synchrotrons, XFELs (X-ray Free Electron Lasers) and high-intensity pulsed electron sources are discussed. They include laser-ON/laser-OFF data scaling, inter- and intra-data set scaling.

New methods in time-resolved Laue pump-probe crystallography at synchrotron sources

Newly developed methods for time-resolved studies using the polychromatic and in particular the pink-Laue technique, suitable for medium and small-size unit cells typical in chemical crystallography, are reviewed. The order of the sections follows that of a typical study, starting with a description of the pink-Laue technique, followed by the strategy of data collection for analysis with the RATIO method. Novel procedures are described for spot integration, orientation matrix determination for relatively sparse diffraction patterns, scaling of multi-crystal data sets, use of Fourier maps for initial assessment and analysis of results, and least-squares refinement of photo-induced structural and thermal changes. In the calculation of Fourier maps a ground-state structure model, typically based on monochromatic results, is employed as reference, and the laser-ON structure factors for the Fourier summations are obtained by multiplying the reference ground-state structure factors by the square root of the experimental ON/OFF ratios. A schematic of the procedure followed is included in the conclusion section.

Perspective: On the relevance of slower-than-femtosecond time scales in chemical structural-dynamics studies

A number of examples illustrate structural-dynamics studies of picosecond and slower photo-induced processes. They include molecular rearrangements and excitations. The information that can be obtained from such studies is discussed. The results are complementary to the information obtained from femtosecond studies. The point is made that all pertinent time scales should be covered to obtain comprehensive insight in dynamic processes of chemical and biological importance.

An optical chopper for generation of short X-ray pulses to allow in-house time-resolved photocrystallography. Corrigendum

In the paper by Kamińskiet al.[J. Appl. Cryst.(2014),47, 1765–1768], Jason B. Benedict is missing from the list of authors. The complete list of authors should be Radosław Kamiński, Jason B. Benedict, Gary Nottingham and Philip Coppens.

Shedding light on the photochemistry of coinage-metal phosphorescent materials: a time-resolved Laue diffraction study of an Ag(I)-Cu(I) tetranuclear complex

The triplet excited state of a new crystalline form of a tetranuclear coordination d(10)-d(10)-type complex, Ag2Cu2L4 (L = 2-diphenylphosphino-3-methylindole ligand), containing Ag(I) and Cu(I) metal centers has been explored using the Laue pump-probe technique with ≈80 ps time resolution. The relatively short lifetime of 1 μs is accompanied by significant photoinduced structural changes, as large as the Ag1···Cu2 distance shortening by 0.59(3) Å. The results show a pronounced strengthening of the argentophilic interactions and formation of new Ag···Cu bonds on excitation. Theoretical calculations indicate that the structural changes are due to a ligand-to-metal charge transfer (LMCT) strengthening the Ag···Ag interaction, mainly occurring from the methylindole ligands to the silver metal centers. QM/MM optimizations of the ground and excited states of the complex support the experimental results. Comparison with isolated molecule optimizations demonstrates the restricting effect of the crystalline matrix on photoinduced distortions. The work represents the first time-resolved Laue diffraction study of a heteronuclear coordination complex and provides new information on the nature of photoresponse of coinage metal complexes, which have been the subject of extensive studies.

An optical chopper for generation of short X-ray pulses to allow in-house time-resolved photocrystallography

As part of a project to implement in-house time-resolved diffraction of short-lifetime species, a fast shutter with a custom-designed enclosure has been installed. The device is suitable for generation of X-ray pulses with time lengths down to about 5 µs. The design does not require major modifications to commercially available diffractometer setups. Significant airflow, generated by the rotating chopper disc, which interferes with temperature control at the sample, has been eliminated by a compact enclosure, which does not interfere with sample monitoring and conditioning devices. It allows for full rotation of the diffractometer circles.

Analysis of multicrystal pump-probe data sets. I. Expressions for the RATIO model

The RATIO method in time-resolved crystallography [Coppens et al. (2009). J. Synchrotron Rad. 16, 226-230] was developed for use with Laue pump-probe diffraction data to avoid complex corrections due to wavelength dependence of the intensities. The application of the RATIO method in processing/analysis prior to structure refinement requires an appropriate ratio model for modeling the light response. The assessment of the accuracy of pump-probe time-resolved structure refinements based on the observed ratios was discussed in a previous paper. In the current paper, a detailed ratio model is discussed, taking into account both geometric and thermal light-induced changes.

On the assessment of time-resolved diffraction results

Dynamic-structure crystallography, and in particular photocrystallography, is a field of great interest because of its numerous applications. The field covers the studies of reactions in crystals including non-reversible reactions, phase transitions and the structure change on excitation leading to short-lifetime species. Data collected during dynamic-structure crystallography experiments require appropriate tools to perform data analysis. The relative scaling of different sets of data recurs in time-resolved pump-probe data collection in which crystals often disintegrate before a full set of data can be collected. We discuss relative scaling and its use with the Ratio method [1], in which ratios of observed intensities collected with and without light-exposure are used as observables. The scaling method has been developed specifically for pump-probe Laue data, but is not limited to polychromatic data sets. The visualization of the externally induced structure changes in the crystal environment is of importance to check the presence of a structural response (see Fig. a) and hence to define a starting point for the structure refinement. For this purpose, ratio-based Fourier difference maps have been defined. After the structure refinement using the software LASER [2], the quality of the light-exposed structure model can be checked in direct space by visualizing the ratio-based Fourier residual maps, and, in a complementary manner, in reciprocal space by performing statistical analysis on the least-squares (LS) residual vector components with respect to the corresponding H-vectors (see Fig. b). The latter allows detection of any outliers or unexpected tendencies such as dependence of the residual vector components on the resolution or the angular direction in the reciprocal space. Application to the complex [Cu(I)-(1,10-phenanthroline-N,N′)bis(triphenylphosphine)][BF4] will be presented [3]. Research supported by the National Science Foundation (CHE1213223).

Selective time-dependent changes of Cu(DPPE)(DMP)·PF6on photoexcitation

Thanks to their potential applications as light-emitting devices, chemical sensors and dye-sensitized solar cells, heteroleptic copper (I) complexes have been extensively studied. Cu(DPPE)(DMP)·PF6(dppe= 1,2-bis(diphenylphosphino)ethane; dmp = 2,9-dimethyl-1,10-phenanthroline) crystallizes in the monoclinic system, P21/c, with two independent molecules in the asymmetric unit. Previous studies on this system [1,2] show strong temperature-dependent emission. The complex was studied at 90K under 355nm laser excitation. At this temperature, the luminescence decay for Cu(DPPE)(DMP)·PF6is biexponential with lifetimes of ~3μs and ~28μs. Two time-resolved X-ray diffraction techniques were applied for studies: (1) a Laue technique at BioCARS ID-14 beamline at the Advanced Photon Source, and (2) monochromatic diffraction at a newly constructed in-house pump-probe monochromatic facility at the University at Buffalo. Structural changes determined with the two methods are in qualitative agreement; discrepancies in position of the Cu and P atoms were observed. The molecular distortions were smaller than those determined at 16K in the earlier synchrotron study by Vorontsov et al. [2]. Photodeformation maps (see Figure below), in which the increase in temperature on photoexcitation has been eliminated, clearly illustrate the photoinduced atomic shifts for both data sets. Results will be compared with those obtained for other studied heteroleptic copper (I) complexes, for instance Cu[(1,10-phenanthroline-N,N′) bis(triphenylphosphine)]·BF4[3]. The in-house pump-probe facility is discussed by Radoslaw Kaminski at this meeting. Research funded by the National Science Foundation (CHE1213223). BioCARS Sector 14 at APS is supported by NIH (RR007707). The Advanced Photon Source is funded by the Office of Basic Energy Sciences, U.S. Department of Energy, (W-31-109-ENG-38). KNJ is supported by the Polish Ministry of Science and Higher Education through the "Mobility Plus" program.

Direct observation of the excited state structure of a Ag(I)-Cu(I) complex

Heterodentate coordination complexes have been extensively studied because of their rich electronic and luminescent properties, which are of importance in the design of molecular devices. The short metal-metal contacts found in such complexes determine the nature of the lowest lying emissive states, and must be explored in order to understand their physical properties. Recent advances in time-resolved (TR) synchrotron techniques supported by specific data collection strategies and data processing procedures [1] allow for elucidation of molecular excited state geometries in the solid state. The approach has been so far successfully applied to several high-quality Laue-data sets collected at the 14-ID BioCars beamline at the Advanced Photon Source.[2] In this contribution we present synchrotron TR experiment results obtained for a new solvent-free crystal form of a model complex containing Ag(I) and Cu(I) (Ag2Cu2L4, L = 2-diphenylphosphino-3-methylindole).[3] This system exhibits red solid-state luminescence with a lifetime of about 1 µs. This is one of the shortest-lived excited states we have studied so far with the Laue technique. The relatively short lifetime goes along with significant structural changes observed upon irradiation, such as, the Ag...Ag distance shortening of about 0.2 Å in the excited state. The results clearly show strengthening of the Ag...Ag interactions suggesting a bond formation upon excitation. The photocrystallographic findings are supported by spectroscopic measurements and quantum computations. The results confirm the triplet nature of the emissive state originating mainly from a ligand-to-metal charge transfer. Research funded by the NSF (CHE1213223). BioCARS Sector 14 is supported by NIH, National Center for Research Resources (RR007707). APS is funded by the U.S. DOE, Office of Basic Energy Sciences (W-31-109-ENG-38). KNJ is supported by the Polish Ministry of Science and Higher Education through the "Mobility Plus" program.

First steps towards time-resolved 'in-house' X-ray diffraction experiments

High-intensity X-ray sources, such as synchrotrons or X-ray free electron lasers, providing up to 100 ps time-resolution allow for studying very short-lived excited electronic states in molecular crystals. Some recent examples constitute investigations of Rh...Rh bond shortening,[1] or metal-to-ligand charge transfer processes in CuI complexes.[2] Nevertheless, in cases in which the lifetime of excited state species exceeds 10 μs it is now possible, due to the dramatic increase in the brightness of X-ray sources and the sensitivity of detectors, to use laboratory equipment to explore structural changes upon excitation. Consequently, in this contribution we present detailed technical description of the 'in-house' X-ray diffraction setup allowing for the laser-pump X-ray-probe experiments within the time-resolution at the order of 10 μs or larger. The experimental setup consists of a modified Bruker Mo-rotating-anode diffractometer, coupled with the high-frequency Nd:YAG laser (λ = 355 nm). The required synchronization of the laser pulses and the X-ray beam is realized via the optical chopper mounted across the beam-path. Chopper and laser capabilities enable high-repetition-rate experiments reaching up to 100 kHz. In addition, the laser shutter is being directly controlled though the original diffractometer software, allowing for collection of the data in a similar manner as done at the synchrotron (alternating light-ON & light-OFF frames). The laser beam itself is split into two allowing for improved uniform light delivery onto the crystal specimen. The designed setup was tested on the chosen set of crystals exhibiting rather long-lived excited state, such as, the Cu2Br2L2 (L = C5H4N-NMe2) complex, for which the determined lifetime is about 100 μs at 90 K. The results shall be presented. Research is funded by the National Science Foundation (CHE1213223). KNJ is supported by the Polish Ministry of Science and Higher Education through the "Mobility Plus" program.

Fleeting Excited States by Synchrotron and In-House Pump-Probe Diffraction

While the geometry of the initial state of chemical reactions is now being studied by electron diffraction methods [1] with further efforts underway at XFEL's, the properties of longer lived molecular excited states remain of crucial importance for the design of photoluminescent devices [2] and as precursors in photochemical reactions and electron transfer into semiconductor nanoparticles. Triplet lifetimes in crystals are temperature dependent, but typical in the ns-ms range. If high luminescence is of importance, the lower part of this range is preferable, for other applications longer lifetimes may be desirable. In the former case time-resolved (TR) synchrotron experimentation, preferable with Laue techniques, is the method of choice, whereas for lifetimes above about 10 µs monochromatic in-house TR methods are increasingly feasible due to the continuing increase in the brightness of commercial X-ray sources and in the efficiency of detectors. The in-house method implemented in our laboratory uses a fast mechanical shutter synchronized with up to 100 kHz high repetition-rate lasers, corresponding to a pulse separation of 10 µs, as discussed in detail in a presentation by Kaminski. A number of synchrotron [3] and in-house experiments on mono- bi- and tetra-nuclear organometallic complexes have been completed and are compared. New methods for inter-sample scaling of multi-sample data sets and for visualization of the geometrical changes increase the sensitivity of the TR methods and allow examination of geometry changes on excitation at conversion percentages of only a few %. Further details will be presented in separate presentations. Research funded by the National Science Foundation (CHE1213223). BioCARS Sector 14 at APS is supported by NIH (RR007707). The Advanced Photon Source is funded by the Office of Basic Energy Sciences, U.S. Department of Energy, (W-31-109-ENG-38).

On the assessment of time-resolved diffraction results

Data collected during dynamic structure pump-probe crystallography experiments require appropriate indicators of agreement and tools to visualize the electron-density distribution changes. Agreement factors based on the ratio of intensities R with and without the external perturbation are shown to be analogous to the R1 and wR2 R factors widely used in standard crystallographic refinements. The η-based R factors, normalized by the average relative intensity change, are significantly larger than R-based values. It is shown that the relative intensity change η-based R factors are not suitable for comparing different data sets. Fourier photodifference maps allow the visualization of the externally induced structural changes in the crystal, but also can be used during refinement to observe residual peaks not yet accounted for by the model and thus monitor the progress of the refinement. The photodeformation maps are a complementary tool to confirm the validity of the final model. Photodeformation maps with equalized laser-on and laser-off thermal motion are used to highlight the structural changes.

A novel manganese-doped large polyoxotitanate nanocluster

The largest manganese-doped polyoxotitanate nanocluster so far, Ti₂₈MnO₃₆(OH)₂(OEt)₄₀, is reported. The coordination of the manganese dopant in polyoxotitanate nanoclusters and the impact of manganese doping on the band gap of the clusters are discussed.

Relating structure and photoelectrochemical properties: electron injection by structurally and theoretically characterized transition metal-doped phenanthroline–polyoxotitanate nanoparticles

Whereas a large number of sensitized polyoxotitanate clusters have been reported, information on the electrochemical properties of the fully structurally and theoretically defined nanoparticles has not been available and is presented here.

On the Biexponential Decay of the Photoluminescence of the Two Crystallographically-Independent Molecules in Crystals of [Cu(I)(phen)(PPh3)2][BF4]

[Cu(I)(phen)(PPh3)2][BF4] crystallizes with two nonsymmetry-related molecules in the asymmetric unit. Synchrotron time-resolved X-ray diffraction experiments have shown that the two independent molecules distort differently on MLCT excitation. The luminescence decay of the crystals is biexponential with two different Stokes-shifts, the more rapid decay corresponding to the shorter wavelength emission. Its amplitude diminishes rapidly with an increase in temperature, indicating that this emission is not due to a thermal activation to a higher state. The double emission is attributed to the presence of two independent molecules with drastically different packing environments. It is concluded that the solid-state environment must be analyzed whenever photochemical properties of molecular solids are reported.

Measuring picosecond excited-state lifetimes at synchrotron sources

A new analysis method for the short excited-state lifetime measurement of photosensitive species in crystals is described. Based on photocrystallographic techniques, this method is an alternative to spectroscopic methods and is also valid for non-luminescent excited species. Two different approaches are described depending on the magnitude of the lifetime τ. For very short lifetimes below the width of the synchrotron pulse, an estimated τ can be obtained from the occurrence of the maximal system response as a function of the pump-probe delay time Δt. More precise estimates for both short and longer lifetimes can be achieved by a refinement of a model of the response as a function of the pump-probe delay time. The method also offers the possibility of the structure determination of excited species with lifetimes in the 40-100 ps range.

The LaueUtil toolkit for Laue photocrystallography. II. Spot finding and integration

A spot-integration method is described which does not require prior indexing of the reflections. It is based on statistical analysis of the values from each of the pixels on successive frames, followed for each frame by morphological analysis to identify clusters of high value pixels which form an appropriate mask corresponding to a reflection peak. The method does not require prior assumptions such as fitting of a profile or definition of an integration box. The results are compared with those of the seed-skewness method which is based on minimizing the skewness of the intensity distribution within a peak's integration box. Applications in Laue photocrystallography are presented.

Interfacial electron transfer into functionalized crystalline polyoxotitanate nanoclusters

Interfacial electron transfer (IET) between a chromophore and a semiconductor nanoparticle is one of the key processes in a dye-sensitized solar cell. Theoretical simulations of the electron transfer in polyoxotitanate nanoclusters Ti(17)O(24)(OPr(i))(20) (Ti(17)) functionalized with four p-nitrophenyl acetylacetone (NPA-H) adsorbates, of which the atomic structure has been fully established by X-ray diffraction measurements, are presented. Complementary experimental information showing IET has been obtained by EPR spectroscopy. Evolution of the time-dependent photoexcited electron during the initial 5 fs after instantaneous excitation to the NPA LUMO + 1 has been evaluated. Evidence for delocalization of the excitation over multiple chromophores after excitation to the NPA LUMO + 2 state on a 15 fs time scale is also obtained. While chromophores are generally considered electronically isolated with respect to neighboring sensitizers, our calculations show that this is not necessarily the case. The present work is the most comprehensive study to date of a sensitized semiconductor nanoparticle in which the structure of the surface and the mode of molecular adsorption are precisely defined.

Ultrafast spin-state photoswitching in a crystal and slower consecutive processes investigated by femtosecond optical spectroscopy and picosecond X-ray diffraction

We report the spin state photo-switching dynamics in two polymorphs of a spin-crossover molecular complex triggered by a femtosecond laser flash, as determined by combining femtosecond optical pump-probe spectroscopy and picosecond X-ray diffraction techniques. The light-driven transformations in the two polymorphs are compared. Combining both techniques and tracking how the X-ray data correlate with optical signals allow understanding of how electronic and structural degrees of freedom couple and play their role when the switchable molecules interact in the active crystalline medium. The study sheds light on crossing the border between femtochemistry at the molecular scale and femtoswitching at the material scale.

Restricted photochemistry in the molecular solid state: structural changes on photoexcitation of Cu(I) phenanthroline metal-to-ligand charge transfer (MLCT) complexes by time-resolved diffraction

The excited-state structure of [Cu(I)[(1,10-phenanthroline-N,N') bis(triphenylphosphine)] cations in their crystalline [BF(4)] salt has been determined at both 180 and 90 K by single-pulse time-resolved synchrotron experiments with the modified polychromatic Laue method. The two independent molecules in the crystal show distortions on MLCT excitation that differ in magnitude and direction, a difference attributed to a pronounced difference in the molecular environment of the two complexes. As the excited states differ, the decay of the emission is biexponential with two strongly different lifetimes, the longer lifetime, assigned to the more restricted molecule, becoming more prevalent as the temperature increases. Standard deviations in the current Laue study are very much lower than those achieved in a previous monochromatic study of a Cu(I) 2,9-dimethylphenanthroline substituted complex ( J. Am. Chem. Soc. 2009 , 131 , 6566 ), but the magnitudes of the shifts on excitation are similar, indicating that lattice restrictions dominate over the steric effect of the methyl substitution. Above all, the study illustrates emphatically that molecules in solids have physical properties different from those of isolated molecules and that their properties depend on the specific molecular environment. This conclusion is relevant for the understanding of the properties of molecular solid-state devices, which are increasingly used in current technology.

The LaueUtil toolkit for Laue photocrystallography. I. Rapid orientation matrix determination for intermediate-size-unit-cell Laue data

A new method for determination of the orientation matrix of Laue X-ray data is presented. The method is based on matching of the experimental patterns of central reciprocal lattice rows projected on a unit sphere centered on the origin of the reciprocal lattice with the corresponding pattern of a monochromatic data set on the same material. This technique is applied to the complete data set and thus eliminates problems often encountered when single frames with a limited number of peaks are to be used for orientation matrix determination. Application of the method to a series of Laue data sets on organometallic crystals is described. The corresponding program is available under a Mozilla Public License-like open-source license.