UV Vis Spectrum Calculator

Enter UV Vis Spectrum Inputs

This calculator uses Beer Lambert scaling and Gaussian peak simulation for up to three absorption bands.

Analyte Name

Sample ID

Solvent

Start Wavelength (nm)

End Wavelength (nm)

Step Size (nm)

Analysis Wavelength (nm)

Band Edge Wavelength (nm)

Used for approximate optical band gap estimation.

Path Length (cm)

Concentration (mol/L)

Baseline Absorbance

Peak 1

Peak 1 Lambda Max (nm)

Peak 1 Molar Absorptivity

Peak 1 FWHM (nm)

Peak 1 Intensity Factor

Peak 2

Peak 2 Lambda Max (nm)

Peak 2 Molar Absorptivity

Peak 2 FWHM (nm)

Peak 2 Intensity Factor

Peak 3

Peak 3 Lambda Max (nm)

Peak 3 Molar Absorptivity

Peak 3 FWHM (nm)

Peak 3 Intensity Factor

Example Data Table

This example shows one possible laboratory setup for a simulated three-band UV Vis scan.

Analyte	Range (nm)	Path Length (cm)	Concentration (mol/L)	Peak Set	Band Edge (nm)
Copper(II) Complex	200 to 800	1.00	0.00015	280 / 510 / 650 nm	620
Peak Widths	35 / 80 / 55 nm	Baseline	0.020 A	Intensity Factors	1.00 / 1.15 / 0.70
Peak Epsilon Values	8500 / 4200 / 1600	Analysis Wavelength	500 nm	Expected Use	Absorbance and band gap review

Formula Used

Beer Lambert law: A = εlc
Transmittance relation: T = 10^-A, and %T = 100 × 10^-A
Gaussian peak model: A(λ) = A_baseline + Σ[A_max,i × exp(-((λ - λ_max,i)² / 2σ²))]
Peak width conversion: σ = FWHM / 2.35482
Apparent molar absorptivity: ε_app = (A - baseline) / (lc)
Absorption coefficient: α = 2.303A / l
Photon energy: E(eV) = 1240 / λ(nm)
Wavenumber: ṽ = 10⁷ / λ(nm)
Frequency: ν = c / λ
Optical band gap estimate: E_g(eV) = 1240 / λ_edge

The simulator combines up to three absorbance bands and adds a baseline offset. It is useful for quick educational studies, pre-lab checks, and method planning.

How to Use This Calculator

Enter the analyte name, sample ID, solvent, and the wavelength scan range.
Set the step size and choose an analysis wavelength inside the scan range.
Provide the path length, sample concentration, and baseline absorbance.
Enter one to three spectral peaks with lambda max, molar absorptivity, width, and intensity factor.
Optionally add a band edge wavelength for approximate optical band gap estimation.
Press Generate Spectrum to calculate absorbance, transmittance, energy, wavenumber, and area values.
Review the result summary above the form, inspect the Plotly graph, and export the report using CSV or PDF.

FAQs

1. What does this calculator estimate?

It estimates a UV Vis absorbance spectrum from up to three Gaussian absorption bands. It also reports transmittance, photon energy, wavenumber, absorption coefficient, and an optical band gap estimate.

2. Why is Beer Lambert law included?

Beer Lambert law links absorbance with molar absorptivity, path length, and concentration. That relationship determines each peak height before the spectrum is simulated across the selected wavelength range.

3. What is the intensity factor?

The intensity factor scales the theoretical peak height. It helps model stronger or weaker bands without changing concentration, path length, or molar absorptivity values.

4. What does FWHM control?

FWHM controls peak width. Smaller values create sharper bands, while larger values broaden the spectral feature and increase overlap between neighboring peaks.

5. Is the optical band gap exact?

No. The band gap value here is a quick estimate from an entered edge wavelength. Precise band gap work often needs Tauc analysis and experimental validation.

6. Can I use this for real instrument data?

Yes, for planning or comparison. However, measured spectra may include noise, solvent effects, scattering, baseline drift, and instrument bandwidth effects not fully modeled here.

7. What does the integrated absorbance area mean?

It is the numerical area under the absorbance curve across the selected wavelength range. This helps compare total spectral strength between simulated samples.

8. Why is transmittance shown with absorbance?

Absorbance and transmittance describe the same optical behavior from different viewpoints. Showing both helps interpret how strongly the sample attenuates incident light.