| Summary: | The electronic surroundings of phosphorus and lithium atoms in the ionic conductor lithium dihydrogen phosphate (LDP) have been studied by single-crystal nuclear magnetic resonance (NMR) spectroscopy at room temperature. From orientation-dependent NMR spectra of a large homegrown LDP single crystal, the full <sup>31</sup>P chemical shift (CS) and <sup>7</sup>Li quadrupole coupling (QC) tensor was determined, using a global fit over three rotation patterns. The resulting CS tensor is characterized by its three eigenvalues: <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>δ</mi> <mrow> <mn>11</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mn>67.0</mn> <mo>±</mo> <mn>0.6</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> ppm, <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>δ</mi> <mrow> <mn>22</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mn>13.9</mn> <mo>±</mo> <mn>1.5</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> ppm, and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>δ</mi> <mrow> <mn>33</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mo>−</mo> <mn>78.7</mn> <mo>±</mo> <mn>0.9</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> ppm. All eigenvalues have also been verified by magic-angle spinning NMR on a polycrystalline sample, using Herzfeld–Berger analysis of the rotational side band pattern. The resulting <sup>7</sup>Li QC tensor is characterized by its quadrupolar coupling constant <inline-formula> <math display="inline"> <semantics> <mrow> <mi>χ</mi> <mo>=</mo> <msubsup> <mi>Q</mi> <mrow> <mn>33</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mo>−</mo> <mn>71</mn> <mo>±</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> kHz and the two eigenvalues <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>Q</mi> <mrow> <mn>11</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mn>22.3</mn> <mo>±</mo> <mn>0.9</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> kHz, and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>Q</mi> <mrow> <mn>22</mn> </mrow> <mrow> <mi>P</mi> <mi>A</mi> <mi>S</mi> </mrow> </msubsup> <mo>=</mo> <mrow> <mo>(</mo> <mn>48.4</mn> <mo>±</mo> <mn>0.8</mn> <mo>)</mo> </mrow> </mrow> </semantics> </math> </inline-formula> kHz. The initially unknown orientation of the mounted crystal, expressed by the orientation of the rotation axis in the orthorhombic crystal frame, was included in the global data fit as well, thus obtaining it from NMR data only.
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