= Joaquin F. Rodriguez-Nieva
{c}
\b[Joaquin F. Rodriguez-Nieva] coauthored the 2015 <graphene> isotope Raman study; the paper gives his MIT physics affiliation.<Probing carbon isotope effects on the Raman spectra of graphene with different ¹³C concentrations by Bruno R. Carvalho and others>[byline and affiliation 3]{ref} His Texas A&M research profile describes nonequilibrium quantum dynamics, thermalization and low-dimensional electronic systems.<Joaquin Rodriguez Nieva profile at Texas A&M University>[Research Interests]{ref}
A useful distinction in a spectroscopic comparison is between an offset and a slope. The isotope study compared Raman positions across excitation energies, providing more information than a peak measured with only one laser.<Probing carbon isotope effects on the Raman spectra of graphene with different ¹³C concentrations by Bruno R. Carvalho and others>[Abstract, excitation-energy comparison]{ref}
For an original linear-model example, suppose two samples have peak wavenumbers
$$
\widetilde\nu_A(E)=2450+40E,\qquad
\widetilde\nu_B(E)=2550+40E,
$$
with $E$ expressed in electronvolts and wavenumbers in inverse centimetres. Both peaks increase by $20\,\mathrm{cm^{-1}}$ between $E=2.0$ and $2.5\,\mathrm{eV}$, although they remain separated by $100\,\mathrm{cm^{-1}}$. Equal excitation-energy slopes do not imply equal peak positions.
Conversely, a constant calibration offset shifts a fitted intercept but leaves the slope unchanged if the same offset applies at every energy. An energy-dependent error can alter the slope itself. Comparing these effects requires specified units and uncertainty for both axes. The numerical lines are invented to illustrate an experimental inference, not fits or individual theoretical contributions attributed to Rodriguez-Nieva.
\Image[https://artsci.tamu.edu/physics-astronomy/_files/_images/_profile-images/rodriguez-joaquin-600x731.jpg]
{title=Joaquin Rodriguez Nieva, portrait identified on his Texas A&M physics profile}
{width=240}
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