336
Asparagine We found only three references to the works describing Raman spectrum of solid asparagine [7, 33, 34]. the frequencies and intensities reported
recently [7] agree well with our spectrum.
Aspartic acid there are only a few papers related to the Raman spectra of aspartic acid [3, 7, 35]. the published data agree well with our spectra regarding peak
positions, but the relative intensities, even among strong peaks, are significantly
different.
Cysteine Raman spectra of solid cysteine were reported in several papers [36–39].
the frequencies in the Raman spectrum of solid L-cysteine, published in 1983 [37],
coincide within 5 cm
−1
with our spectra. the exceptions are (i) the peak reported
at 931 cm
−1
, corresponding to our value of 944 cm
−1
; (ii) a peak we observe at
1069 cm
−1
, which was not mentioned. No intensities were reported in this work. In
a recent paper [39], the frequency of 944 cm
−1
was given, in exact agreement with
our results; a peak corresponding to our 1069 cm
−1
band is reported at 1064 cm
−1
.
Glutamine very few studies have been devoted to the Raman spectroscopy of solid
glutamine [7, 40, 41]. our data compare well with those reported by Culka et al. [7].
Glutamic acid Literature reports on the Raman spectroscopy of glutamic acid are
limited to a few papers [3, 7, 42, 43]. our spectra agree very well with those published by Culka et al. [7]. on the contrary, comparison with the spectra reported by
Zhu [3] reveals significant differences in peak positions. most probably, these authors used another crystalline form of this substance.
Isoleucine our spectra agree well with those reported by Zhu et al. [3] and Almeida
et al. [44] with regard to the observed frequencies. A band we observe at 925 cm
−1
was reported by Zhu at 918 cm
−1
; this band was observed by Almeida for L-isoleucine crystals at 922 or 924 cm
−1
, depending on the scattering geometry. Interestingly, the Raman spectrum reported by Sabino et al. in a study of high pressure
effects [45] is quite different with regard to both peak locations and intensities, even
though the authors claim to have used the same crystal form as Almeida.
Leucine Raman spectra of solid leucine have been reported in a number of papers
[3, 46–52]. our spectra agree very well with those of Zhu et al. [3], although the
relative intensities are somewhat different.
Histidine Not much work has been reported for solid histidine [3, 53]. our data
agree with those by Zhu et al. [3]. A Raman spectrum reported for NaBF 4 —doped
L-histidine [54] is completely different.
Lysine our spectra agree nicely with those of Zhu [3]. Aliaga et al. [55] reported the
Raman spectrum of solid lysine which resembles our spectrum in the high energy
region, but is different in the range below 1000 cm
−1
.
Methionine the published Raman spectra of solid methionine [3, 7, 56, 57] agree
well with our spectra with respect to both frequencies and intensities.
T. Roliński et al.
Asparagine We found only three references to the works describing Raman spectrum of solid asparagine [7, 33, 34]. the frequencies and intensities reported
recently [7] agree well with our spectrum.
Aspartic acid there are only a few papers related to the Raman spectra of aspartic acid [3, 7, 35]. the published data agree well with our spectra regarding peak
positions, but the relative intensities, even among strong peaks, are significantly
different.
Cysteine Raman spectra of solid cysteine were reported in several papers [36–39].
the frequencies in the Raman spectrum of solid L-cysteine, published in 1983 [37],
coincide within 5 cm
−1
with our spectra. the exceptions are (i) the peak reported
at 931 cm
−1
, corresponding to our value of 944 cm
−1
; (ii) a peak we observe at
1069 cm
−1
, which was not mentioned. No intensities were reported in this work. In
a recent paper [39], the frequency of 944 cm
−1
was given, in exact agreement with
our results; a peak corresponding to our 1069 cm
−1
band is reported at 1064 cm
−1
.
Glutamine very few studies have been devoted to the Raman spectroscopy of solid
glutamine [7, 40, 41]. our data compare well with those reported by Culka et al. [7].
Glutamic acid Literature reports on the Raman spectroscopy of glutamic acid are
limited to a few papers [3, 7, 42, 43]. our spectra agree very well with those published by Culka et al. [7]. on the contrary, comparison with the spectra reported by
Zhu [3] reveals significant differences in peak positions. most probably, these authors used another crystalline form of this substance.
Isoleucine our spectra agree well with those reported by Zhu et al. [3] and Almeida
et al. [44] with regard to the observed frequencies. A band we observe at 925 cm
−1
was reported by Zhu at 918 cm
−1
; this band was observed by Almeida for L-isoleucine crystals at 922 or 924 cm
−1
, depending on the scattering geometry. Interestingly, the Raman spectrum reported by Sabino et al. in a study of high pressure
effects [45] is quite different with regard to both peak locations and intensities, even
though the authors claim to have used the same crystal form as Almeida.
Leucine Raman spectra of solid leucine have been reported in a number of papers
[3, 46–52]. our spectra agree very well with those of Zhu et al. [3], although the
relative intensities are somewhat different.
Histidine Not much work has been reported for solid histidine [3, 53]. our data
agree with those by Zhu et al. [3]. A Raman spectrum reported for NaBF 4 —doped
L-histidine [54] is completely different.
Lysine our spectra agree nicely with those of Zhu [3]. Aliaga et al. [55] reported the
Raman spectrum of solid lysine which resembles our spectrum in the high energy
region, but is different in the range below 1000 cm
−1
.
Methionine the published Raman spectra of solid methionine [3, 7, 56, 57] agree
well with our spectra with respect to both frequencies and intensities.
T. Roliński et al.