Two-dimensional infrared correlation spectroscopy of synthetic and biological apatites

Influence of phosphonation and phosphation on surface acid–base and morphological properties of CaO as investigated by in situ FTIR spectroscopy and electron microscopy

“…Also, the corresponding ν 4 absorption was resolved into eight peaks at 655, 633, 613, 603, 586, 577, 566, and 548 cm −1 . Similar results were obtained for the same material, using either second-derivative [18,19] or two-dimensional (2D) [20] IR spectroscopy. On the other hand, protonated phosphate groups, i.e., H 2 PO − 4 or HPO 2− 4 , give rise to νPO-H at 2700-2650 cm −1 , whereas polymerized phosphates, i.e., P 2 O 4− 7 , exhibit νP=O at 1320-1250 cm −1 (often a doublet) and νP-O-P at 980-900 cm −1 [16].…”

Apatite and Portland/apatite composite cements obtained using a hydrothermal method for retaining heavy metals

“…In addition to these bands, the MA1 ceramic shows bands at 1142 cm −1 whose ascription is slightly controversial. While Gadaleta et al [30] attribute this band to PO 4 vibrations in an apatitic environment of poorly crystalline hydroxyapatite, most of the authors associate this band to the presence of HPO 4 2− groups in nonstoichiometric HAp or to the existence of calcium phosphate phases more acidic than HAp as TCP, OCP, DCPD or DCPA [31,32]. The presence of TCP and OCP in both MA1 and MA2 ceramics is stated by XRD and SEM-EDX analysis, which supports the ascription of this band to HPO 4 2− vibrational modes.…”

Potential of two-dimensional correlation spectroscopy in analyses of NIR spectra of biological fluids. I. Two-dimensional correlation analysis of protein and fat concentration-dependent spectral variations of milk

“…Since 1993, generalized 2D correlation spectroscopy has been applied to various subjects for basic research [12][13][14][15][16][17][18][19][20][21]. For example, temperature-dependent NIR spectral variations of self-associated molecules such as alcohols and amides [ 1 3 , 1 6 ] , and the secondary stru c t u res of proteins [19,20] we re inve s t i gated by ge n e ra l i zed 2D corre l ation spectroscopy.…”