Transient-Absorption Lifetime Fit
Fit a positive transient-absorption trace to a single exponential using log-linear regression.
Description
A single-exponential lifetime can be fitted by regressing log signal against time.
A single-exponential lifetime can be fitted by regressing log signal against time. This weights deviations in logarithmic signal rather than original signal.1
Fit a positive transient-absorption trace to a single exponential using log-linear regression.
When to use Transient-Absorption Lifetime Fit
Use this tool to fit a positive transient-absorption trace to a single exponential using log-linear regression.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Transient-Absorption Lifetime Fit and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter timesPicoseconds, signals using the field table and calculation rules, then run the tool.
- Read lifetimePicoseconds, initialAmplitude, rSquared. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| timesPicoseconds | Delay times (ps) | list of number | Required |
| signals | Transient-absorption signals | list of number | Required |
Enter at least two aligned finite times in ps and positive signals. Times need variation but need not be sorted. Fit ordinary least squares and reject nonnegative slope. Return lifetime, zero-time amplitude and log-space R².
ln(signal)=intercept+slope×time; lifetime=−1/slope; amplitude=exp(intercept) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| lifetimePicoseconds | Exponential lifetime (ps) | number; minimum: 0 |
| initialAmplitude | Fitted initial amplitude | number; minimum: 0 |
| rSquared | Log-linear fit R squared | number; maximum: 1 |
{
"input": {
"timesPicoseconds": [
0,
1,
2
],
"signals": [
1,
0.36787944117144233,
0.1353352832366127
]
},
"output": {
"lifetimePicoseconds": 1,
"initialAmplitude": 1,
"rSquared": 1
}
}Limitations and assumptions
No baseline, multiexponential components, instrument response or fit uncertainty is included.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use FLIM Mean Lifetime: Calculate a count-weighted mean fluorescence lifetime from a supplied histogram. For a complementary task, use SRS Contrast: Calculate stimulated Raman loss contrast from pump-on and pump-off probe measurements.
References
-
Transient-Absorption Lifetime Fit — tool.io
Similar or alternative tools
- FLIM Mean Lifetime
Calculate a count-weighted mean fluorescence lifetime from a supplied histogram.
- SRS Contrast
Calculate stimulated Raman loss contrast from pump-on and pump-off probe measurements.