From your spectrum to the result, step by step.

The DiffAtOnce workflow

DiffAtOnce Legacy preserves the original idea: spectra → resonances → editable attenuation → calibrated diffusion → shape and size. Work with a specific resonance and ramp; their exclusions, parameters and stored results remain separate.

D is the translational diffusion coefficient. Rh is an equivalent hydrodynamic radius under the chosen conditions and model. Mass inferred from D is apparent and depends on an empirical calibration. A ppm match, high R² or an ellipsoid illustration does not confirm identity, purity or molecular geometry.

Original spectra are retained. Editable fields, intensities used, decisions and stored results are distinct states. A change that affects calculation makes the previous results stale until recalculation. The synthetic example explores the software and is labelled accordingly.

Start an analysis

1. Open a JSON project or use Importar Bruker / Importar CSV. Review provenance and diagnostics in Proyecto.
2. In Espectros, choose a compatible acquisition and press Usar serie. Check gradients, nucleus, pulse program and timing.
3. Enable Seleccionar resonancias and click a peak crest. Review the monitored point and its local window.
4. In Difusión, review the tail and included points; fit the line and calculate D using a calibrated gradient or reference.
5. Review temperature, viscosity and an internal standard where appropriate. Then inspect Forma y tamaño and microfriction convergence.
6. Enable a mass conversion only after reviewing applicability. Save the project and export a report for the current result.

Save throughout your work. Clicking an existing resonance line selects it without creating a duplicate. Spanish control labels are retained here so that you can find them in the main interface.

Import spectra and CSV

The reader handles processed Bruker data: 1r/procs and pseudo2D 2rr/procs/proc2s. It does not process raw FIDs. Numeric type, byte order and NC_proc scaling are respected; truncated files or incompatible dimensions produce a diagnostic.

For pseudo2D data, confirm that the indirect axis represents diffusion and that each row has its associated gradient. Review padding rows. The presence of 2rr alone does not establish that an experiment is DOSY.

Under Proyecto → Opciones de importación Bruker, select processing number, GPZ index and gradient-list units. The initial index is GPZ[6]; check whether your sequence uses another entry. A list may declare percent or fraction; units are not guessed from magnitude and missing values are not changed to zero.

An attenuation CSV accepts gradient_percent and one intensity column per resonance. Name__included retains the selection. Semicolon separators and decimal commas are supported. A spectrum CSV uses ppm,intensity, a strictly monotonic axis and an optional constant gradient_percent. Keep the .metadata.json companion file when exporting CSV.

Series and ramps of any length

Ramps are grouped using acquisition metadata and gradient resets. Names and boundaries need not be 10–32: a ramp may start at 1, contain 22 acquisitions or have another length. Every imported acquisition is retained, and points remain associated with their actual experiment.

If pulse programs or timing differ, select a candidate in Espectros and press Usar serie before calculation. Do not combine incompatible blocks simply to complete a line. Missing gradients require review or explicit entry.

Parameters and results are stored per resonance and ramp. Switching ramps restores that ramp's configuration, temperature, viscosity and mass estimate. Check the active scope before interpreting or exporting numbers.

Automatic detection proposes an association from the available data; review the boundaries and program. Folder numbering or a plausible length does not validate an acquisition.

Select a peak crest

Enable Seleccionar resonancias and click once on the spectrum. The click snaps to the highest original sample within a small horizontal neighbourhood of the displayed view. This visual tolerance follows zoom; it is neither ppm uncertainty nor a change to the scientific tracking window.

From that centre, the software finds the highest original intensity within the local neighbourhood of each spectrum. The initial window is ±26 samples, clipped at spectrum boundaries, and may also be limited in ppm. It does not use a global maximum, absolute intensity or an interpolated crest.

You can enter ppm manually. If the window contains a higher overlapping signal, narrow it or choose another resonance. A maximum at the window edge calls for review. A higher peak outside the neighbourhood must not attract tracking.

Click an existing line to select its resonance. Every resonance keeps its own attenuation, mask and calculations. The wheel zooms, dragging pans and right-click resets the view.

Monitored point and re-extraction

The glowing point identifies an original spectral sample. Automático displays the highest local maximum among included spectra for that resonance. Referencia fija inspects a chosen experiment. Changing only the visual reference does not alter intensities, exclusions, D, Rh or mass.

In Punto monitorizado y ventana, inspect ppm, sample, spectrum and window boundaries. Reports distinguish I espectral original (original spectral intensity) from I utilizada (intensity used): an edited attenuation value can differ from the original crest.

Volver a localizar re-extracts maxima with the specified window. Centrar en cima explicitly recentres a saved signal on a flank and re-extracts it in the current view. Both retain the previous history, gradients and manual exclusions; review the tail and recalculate afterwards.

Labels associated with the previous centre remain documented in history for review; they are not reassigned automatically. Attenuation CSV or historical data without spectra do not receive invented original positions. Samples displayed to users are 1-based; stored array indices are 0-based.

Attenuation, selection and noise tail

The line fits y = ln(I/I0) against x = (g/100)² using unweighted ordinary least squares. Slope, intercept, r, R², standard error and residuals are shown. I0 is retained even when its acquisition is excluded from fitting.

Click a point to include or exclude it; intensity and gradient can also be edited in the table. Decisions persist per resonance and ramp. Editing data invalidates the fit and derived results. The logarithm requires positive intensities; signs are not rectified and zeros are not replaced with small positive values.

Revisar cola proposes excluding a terminal region compatible with a signal floor or noise. It does not impose a universal x=0.5 cutoff. It uses an attenuating prefix and low-signal evidence; full spectra may provide a noise estimate, while data without spectra receive a conservative review. A positive plateau or smooth curvature can indicate overlap or multiple components and is not removed merely to improve R².

You may declare Umbral relativo manual · %, an operational criterion rather than certified uncertainty. Restaurar cola reverses that automatic exclusion. Original points remain intact and manual exclusions stay independent. Always inspect the diagnostic and residuals.

Calculate D and correct conditions

Check nucleus and angular γ, pulse sequence, gradient shape, δ per lobe, Δ and BPP gap. PGSE/PGSTE and STE-BPP calculations support rectangular or sine gradients. Historical SMSQ and double-sequence branches are not presented as calculated without reviewing their equations.

Absolute calculation requires a calibrated maximum gradient. The external-reference route needs compatible reference D and slope, nucleus, program, timing, shape and temperature. A nominal gradient or complete metadata does not replace experimental calibration.

Sugerir patrón interno… compares candidates compatible with nucleus and matrix: solvent, TTMS, TSP, TMS and other available records. Check companion windows, overlap and identity before confirmation. A signal near zero alone does not establish TMS or TTMS.

Factors remain separate: Dfinal = Dbase × fstandard × fT × fη. The internal-standard factor is expected D at measurement temperature divided by the standard's measured base D. Normalizar temperatura uses target/measurement temperature; Corregir también viscosidad requires target viscosity. Do not apply factors already incorporated a second time.

Effective conditions accompany the result. D uses m²/s; display values may use ×10⁻⁹ m²/s. Temperature uses K, viscosity mPa·s, times ms and maximum gradient T/m. Check units: 1 G/cm = 0.01 T/m and 1 G/mm = 0.1 T/m.

Approximate shape and size

In Forma y tamaño, Rh follows Stokes–Einstein: Rh = kB T / (6π η D). Viscosity is converted to Pa·s and radius is reported in Å. This is an equivalent radius, not a directly measured semiaxis.

A sphere has equal axes. For a cylinder, P = a/b; length = 2a and diameter = 2b. For an ellipsoid, Q = b/a: Q<1 is elongated prolate, Q>1 flattened oblate and Q=1 the spherical limit. The illustrations respond to those parameters.

Sugerir forma… requires geometric evidence and provenance, such as dimensions or suitable structural information. Review anisotropy, symmetry and limits before applying a proposal. Scalar D, ppm or a spectral family cannot uniquely determine geometry or justify an invented Q.

For a flexible chain or branched structure, state which conformation or equivalent solid the approximation represents. Family guidance provides context without automatically applying a shape. Select the models used in spectrum panels and calculate all resonances to update their estimates.

Wirtz, Chen and convergence

Wirtz and Chen microfriction corrections use the equivalent solvent radius and the selected model's radius. They retain the inherited equations and a self-consistent iteration. Inspect each shape separately: sphere, cylinder and ellipsoid.

Review solvent radius, factor, iteration history, number of steps and diagnostic. Convergido means the numerical criterion was met; it does not establish physical applicability. A non-converged result is not published as a valid final number; its provisional history remains available.

The microfriction choice changes a model estimate, not the original spectrum or signal identity. Do not interpret stable iteration as validation of an absolute molecular radius. Preserve the chosen model and conditions in the project.

Identify regions and families

Enable Zonas moleculares to inspect indicative bands. Zonas y tipos… compares the monitored point's ppm, nucleus and solvent with chemical regions, candidate families and molecule references. Moléculas y picos browses the documentary library.

Regions may overlap. Teaching intervals, material examples and individual molecule references have different roles; their sources and conditions remain visible. Operational search padding is distinguished from the published interval and is not experimental uncertainty.

Check companion signals, multiplicity and matrix. The count of compatible windows is not an identity probability or confirmation of connectivity. Some families require manual consultation because a single ppm does not provide sufficient evidence.

Saving a family or label is an explicit decision per resonance. It does not change D, Rh, Q or the mass curve. Review the label after changing centre, window or context; previous observations and sources remain documented.

Apparent molecular mass

Estimation starts disabled. In Masa molecular, select a resonance/ramp with a current D and review method, solvent, temperature, viscosity and provenance. Temperature and viscosity belong to that ramp's D calculation; standard and thermal corrections are not applied again.

Alta dilución requires PS or PPG selection. Each curve has its own coefficients. A concentración uses a historical common model of PS origin; it does not add a correction on top of PS/PPG and has no PPG concentration variant.

For concentration, enter solute and solvent masses in mg. C = msolute/msolvent, not percent or total solution mass. A revised exponent ν or constant k requires a documented parameter source.

Curves compare scenarios for the same D. The point represents the active estimate; D ±25% sensitivity keeps other parameters fixed and is not a confidence interval. The model discontinuity at 117000 Da retains a gap with no solution: mass is not interpolated across it.

M is in Da; molar mass in g/mol shares its numeric value. It is an apparent mass, not Mn, Mw or PDI. Linear-polymer calibrations do not validate absolute masses of stars, brushes or branched resins. Slope-derived propagated errors are partial 1 SE, without calibration uncertainty or a 95% interval. Unsupported or stale results do not receive fabricated numbers.

PDF, PS, EPS, Excel and CSV reports

Exportar informe offers PDF, PostScript, attenuation/spectrum EPS and Excel. Export the current result of the selected resonance and ramp. The program verifies that current points match the stored fit; edited data or ambiguous scope require recalculation or the correct calculation selection.

PDF and PS are multipage vector documents with method, selection, conditions, plots, shape, microfriction, mass and sources. PS is genuine PostScript rather than a renamed PDF. Opening or printing PS needs a compatible viewer or workflow; exporting it requires neither Office nor Adobe.

EPS contains a single-page vector plot with explicit bounds. Spectrum EPS requires available spectra; it does not reconstruct a missing curve from attenuation CSV. PDF and PS retain the monitored maximum and distinguish original intensity from intensity used.

Excel has eight sheets: Resumen, Adquisición, Patrón, Puntos, Geometría, Procedencia, Método y ecuaciones and Masa molecular. Puntos retains 24 selection/tracking columns. Numbers and sources are editable; there are no hidden formulas or experimental precision implied by the displayed decimal places.

CSV retains intensities, gradients and __included; its .metadata.json adds units, SHA-256, conditions, results and decisions. Keep both files. The format matches the extension. Documented D/Rh/mass errors are conditional on fitting rather than total experimental uncertainties.

Save, reopen and preserve provenance

Guardar creates a versioned JSON project containing spectra, resonances, masks, editable values, ramp-specific results, decisions, labels, history and import hashes. Writing is atomic. Reopening preserves that state; saving a draft does not turn it into an updated calculation.

In Proyecto, review the path, notes and diagnostics. Keep original experimental files and your local library alongside working backups. A hash documents integrity, not chemical accuracy or calibration.

Importar proyecto legado recovers available scientific records from the historical archive. It does not invent spectra, excluded points that were never saved or absent acquisitions. A reproduced archived fit is a historical result rather than a new measurement.

A lost or blocked licence does not delete your files. Save a recoverable project copy; file recovery and licence consultation are separate from scientific approval of the analysis.

Local library and custom sequences

In Biblioteca, consult standards, nuclei, viscosities and sequences. Nuevo registro, Editar parámetros, Guardar biblioteca, Importar JSON and Exportar JSON maintain a local library with units and provenance.

Aplicar selección copies the chosen entry into working fields. Review values before calculating; editing an entry does not make its provenance a validated calibration. Viscosity equations preserve temperature range and logarithm base; calculation is blocked outside the range.

Expresiones D/P defines custom sequences with additions and subtractions of experimental Dn/Pn parameters. D in seconds and P in microseconds are converted to ms. It does not execute arbitrary code or invent missing parameters. Different acquisition timings require a compatible selection.

Molecule catalogues and mass calibrations retain their sources. Review evidence before transferring an entry to another matrix or molecular architecture.

Installation, registration and licence

DiffAtOnce Legacy 2.6.1 is distributed for 64-bit Windows in a ZIP with the .NET 10 runtime included. Extract the complete folder and use its launcher. Keep executable, libraries, data and documents together. Office is not needed to calculate or export reports.

Registration is manual by default: complete the installation request and wait for administrator approval. Approval and blocking are managed through the installation portal; submitting a request is not an approved licence.

The licence is checked at startup and periodically every 15 minutes. Validity is reviewed every minute. A signed licence enables the configured offline period: 24 hours by default, administratively configurable from 1 to 168 hours. This is a licensing period rather than permission to ignore expiry or blocking.

Without connectivity, inspect the displayed state and remaining period. If it expires or is blocked, save and retain your work; experimental files and projects are not deleted. Recovering a project does not alter licence status. Do not change the clock, signature or licence files to simulate approval.

Visit diffatonce.com. Installation administration requires authorised access. Bilingual help does not mean every main-interface control has been translated into English.

Resolve common messages

• Mixed programs or timings: select a compatible series before calculation; retain the others for review.
• Missing gradient or uncertain units: review GPZ/list settings and declare units. Do not automatically substitute zero or an assumed ramp.
• Cannot select a peak: enable Seleccionar resonancias, click the trace or an existing line and check zoom. A project without spectra cannot locate an original crest.
• The point is on a flank: review reference/window and explicitly use Centrar en cima; then review the tail and recalculate.
• Non-positive intensity: inspect phase, baseline, overlap and tail; do not take absolute values to force the logarithm.
• No convergence or no mass: inspect diagnostic, parameters, support and applicability. Missing output is preferable to a fabricated number.
• Stale result or rejected report: recalculate using current points and scope. Changing only a visual reference preserves calculation; editing data or re-extraction invalidates it.
• Pending/offline/expired licence: review status, connection and period; save the project and contact administration.

Shortcuts and using this help

• F1: open this guide from the application. Ctrl+O: open project. Ctrl+S: save. Ctrl+Enter: calculate.
• Wheel: zoom a plot. Drag: pan; use Ctrl+drag for attenuation. Right-click: reset view. With the plot focused, Home or Escape also reset it.
• Click in attenuation: toggle point inclusion. Click in spectrum with selection enabled: create/select a resonance.
• In this help, Ctrl+F focuses search, Escape closes and the Español / English selector changes content. Search ignores case and accents and also searches article text.

Help text can be selected and copied. Choosing an article or language does not modify your project. External links open only when clicked; reading the integrated content does not require a network connection.