An NMR spectrum plots signal intensity versus chemical shift (in ppm) to reveal the electronic environment of atomic nuclei in a molecule. It is the primary analytical tool in organic chemistry for determining molecular structure, with peak positions indicating functional groups and splitting patterns (multiplets) revealing connectivity between neighboring atoms. The x-axis is conventionally reversed (high ppm on the left) and peaks appear as sharp signals rising from a baseline.
# anyplot.ai
# spectrum-nmr: NMR Spectrum (Nuclear Magnetic Resonance)
# Library: makie 0.22.10 | Julia 1.11.9
# Quality: 88/100 | Created: 2026-06-03
using CairoMakie
using Colors
using Random
Random.seed!(42)
# Theme tokens
const THEME = get(ENV, "ANYPLOT_THEME", "light")
const PAGE_BG = THEME == "light" ? colorant"#FAF8F1" : colorant"#1A1A17"
const ELEVATED_BG = THEME == "light" ? colorant"#FFFDF6" : colorant"#242420"
const INK = THEME == "light" ? colorant"#1A1A17" : colorant"#F0EFE8"
const INK_SOFT = THEME == "light" ? colorant"#4A4A44" : colorant"#B8B7B0"
const INK_MUTED = THEME == "light" ? colorant"#6B6A63" : colorant"#A8A79F"
const IMPRINT_PALETTE = [
colorant"#009E73", colorant"#C475FD", colorant"#4467A3", colorant"#BD8233",
colorant"#AE3030", colorant"#2ABCCD", colorant"#954477", colorant"#99B314",
]
# Data: synthetic 1H NMR spectrum of ethanol (CH3CH2OH) at 300 MHz
lorentz(x, x0, w, h) = h * (w / 2)^2 / ((x - x0)^2 + (w / 2)^2)
n_pts = 5000
ppm_min = -0.5
ppm_max = 5.5
ppm_vals = collect(range(ppm_min, ppm_max, length = n_pts))
J = 7.0 / 300.0 # coupling constant in ppm at 300 MHz spectrometer
pw = 0.008 # Lorentzian half-width for sharp peaks (ppm)
# TMS reference at 0.0 ppm (singlet)
intensity = lorentz.(ppm_vals, 0.0, 0.006, 0.25)
# CH3 triplet at 1.18 ppm — 1:2:1 relative heights
intensity .+= lorentz.(ppm_vals, 1.18 - J, pw, 1.0)
intensity .+= lorentz.(ppm_vals, 1.18, pw, 2.0)
intensity .+= lorentz.(ppm_vals, 1.18 + J, pw, 1.0)
# OH singlet at 2.61 ppm — broader due to hydrogen-bonding exchange
intensity .+= lorentz.(ppm_vals, 2.61, 0.018, 1.5)
# CH2 quartet at 3.69 ppm — 1:3:3:1 relative heights
intensity .+= lorentz.(ppm_vals, 3.69 - 1.5 * J, pw, 1.0)
intensity .+= lorentz.(ppm_vals, 3.69 - 0.5 * J, pw, 3.0)
intensity .+= lorentz.(ppm_vals, 3.69 + 0.5 * J, pw, 3.0)
intensity .+= lorentz.(ppm_vals, 3.69 + 1.5 * J, pw, 1.0)
# Baseline noise (low SNR — realistic clean spectrum)
intensity .+= 0.015 .* randn(n_pts)
intensity .= max.(intensity, 0.0)
# Title
title_str = "Ethanol ¹H NMR · spectrum-nmr · julia · makie · anyplot.ai"
n_chars = length(title_str)
title_fontsize = n_chars > 67 ? max(14, round(Int, 20 * 67 / n_chars)) : 20
# Figure — landscape 3200x1800
fig = Figure(
size = (1600, 900),
fontsize = 14,
backgroundcolor = PAGE_BG,
)
ax = Axis(
fig[1, 1];
title = title_str,
titlesize = Float32(title_fontsize),
titlecolor = INK,
xlabel = "Chemical Shift (ppm)",
ylabel = "Intensity (a.u.)",
xlabelcolor = INK,
ylabelcolor = INK,
xlabelsize = 14,
ylabelsize = 14,
xticklabelcolor = INK_SOFT,
yticklabelcolor = INK_SOFT,
xticklabelsize = 12,
yticklabelsize = 12,
xtickcolor = INK_SOFT,
ytickcolor = INK_SOFT,
backgroundcolor = PAGE_BG,
topspinevisible = false,
rightspinevisible = false,
leftspinecolor = INK_SOFT,
bottomspinecolor = INK_SOFT,
xgridvisible = false,
ygridvisible = false,
xreversed = true,
limits = (ppm_min, ppm_max, -0.1, 3.8),
)
# Shaded area under spectrum trace (filled before the line to stay behind it)
band!(ax, ppm_vals, zeros(n_pts), intensity; color = (IMPRINT_PALETTE[1], 0.15))
# NMR spectrum trace
lines!(ax, ppm_vals, intensity; color = IMPRINT_PALETTE[1], linewidth = 1.5)
# Peak assignment labels
text!(ax, 1.18, 2.2;
text = "1.18 ppm\nCH₃ (t)",
align = (:center, :bottom),
color = INK_SOFT,
fontsize = 13,
)
text!(ax, 2.61, 1.65;
text = "2.61 ppm\nOH (s)",
align = (:center, :bottom),
color = INK_SOFT,
fontsize = 13,
)
text!(ax, 3.69, 3.15;
text = "3.69 ppm\nCH₂ (q)",
align = (:center, :bottom),
color = INK_SOFT,
fontsize = 13,
)
text!(ax, 0.0, 0.4;
text = "TMS",
align = (:center, :bottom),
color = INK_MUTED,
fontsize = 11,
)
save("plot-$(THEME).png", fig; px_per_unit = 2)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/spectrum-nmr/makie/code. Any spec id and library id listed in llms-full.txt fit the same URL shape; every URL below is complete and callable.
{
"spec_id": "spectrum-nmr",
"language": "julia",
"library": "makie",
"page": "https://anyplot.ai/spectrum-nmr/julia/makie",
"hub": "https://anyplot.ai/spectrum-nmr",
"code_json": "https://api.anyplot.ai/specs/spectrum-nmr/makie/code",
"spec_json": "https://api.anyplot.ai/specs/spectrum-nmr",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/julia/makie/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/julia/makie/plot-dark.png",
"quality_score": 88.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of NMR Spectrum (Nuclear Magnetic Resonance) on anyplot.ai.