1H-NMR and 13C-NMR are both types of nuclear magnetic resonance spectroscopy, but they focus on different nuclei. 1H-NMR targets the hydrogen (proton) nuclei in a molecule, providing information about the number, type, and environment of hydrogens present. In contrast, 13C-NMR targets the carbon-13 isotope, offering insights into the number and types of carbon environments in a molecule. Since only about 1.1% of naturally occurring carbon is carbon-13, 13C-NMR signals are inherently weaker than 1H-NMR signals. However, both techniques are complementary and, when used together, provide a comprehensive understanding of a molecule's structure.

Broad or diffuse peaks in an NMR spectrum can arise from various factors. One common reason is molecular motion, such as rotation or tumbling, which can cause line broadening if it occurs at a rate similar to the difference in energy between nuclear spin states. Additionally, interactions between nuclei, like strong coupling or exchange processes, can lead to broadened peaks. Impurities or solvent interactions can also cause peak broadening. In some cases, especially in solid-state NMR, the lack of rapid molecular motion can lead to inherently broader lines due to the multitude of slightly different environments experienced by nuclei.

Temperature can have several effects on an NMR spectrum. As temperature increases, molecular motion, like rotation or tumbling, becomes faster. If this motion averages out certain nuclear interactions, it can lead to changes in peak positions or shapes. Additionally, temperature can influence chemical equilibria in a sample, potentially shifting the balance between different species and thus altering the relative intensities of their respective signals. Some exchange processes, where nuclei rapidly switch between different environments, might only be observable at certain temperatures. Therefore, temperature control is essential when acquiring NMR spectra, especially when studying dynamic processes or temperature-sensitive equilibria.

The strength of the external magnetic field plays a pivotal role in the resolution of an NMR spectrum. A stronger magnetic field leads to a greater difference in energy between the nuclear spin states, which translates to a larger frequency difference between resonances. This increased separation allows for better resolution of closely spaced signals, enabling the differentiation of protons in similar, but not identical, environments. High-resolution NMR instruments typically operate at higher magnetic field strengths to provide detailed structural information about complex molecules.

Tetramethylsilane (TMS) is widely used as a reference in NMR spectroscopy due to several advantageous properties. Firstly, TMS has a high number of equivalent protons, resulting in a strong and sharp signal. Secondly, its protons are well shielded, causing it to resonate at a higher field (lower ppm) than most other compounds, typically at 0 ppm. This makes it an excellent internal standard. Additionally, TMS is chemically inert, ensuring it doesn't react with the sample. Lastly, it's easily removed from samples due to its volatility, making post-spectroscopy sample recovery straightforward.