Neutron diffraction investigations of L- and D-alanine at different temperatures: The search for structural evidence for parity violation
C. Wilson; Minakshi Ghosh; L. Johnson; Dean Myles; Wenging Wang.; New J.Chem.(Nouv.J.Chim.)  (2005) –; doi:

data_7050082
_publ_section_title
;
Neutron diffraction investigations of L- and D-alanine
at different temperatures: The search for structural evidence for
parity violation
;
_journal_name_full               'New J.Chem.(Nouv.J.Chim.)'
_journal_year                    2005
_chemical_formula_sum            'C3 H7 N O2'
_chemical_formula_weight         89.00
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.000
_cell_angle_beta                 90.000
_cell_angle_gamma                90.000
_cell_formula_units_Z            4
_cell_length_a                   6.043(3)
_cell_length_b                   12.337(5)
_cell_length_c                   5.784(3)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    295(1)
_cell_measurement_theta_min      ?
_cell_volume                     431.21
_diffrn_ambient_temperature      295(1)
_diffrn_measurement_device       SXD
_diffrn_measurement_method       'time-of-flight LAUE diffraction'
_diffrn_radiation_monochromator  none
_diffrn_radiation_probe          neutron
_diffrn_radiation_source         'ISIS spallation source'
_diffrn_radiation_type           neutron
_diffrn_radiation_wavelength     0.5-5.0
_diffrn_reflns_av_R_equivalents  0.071
_diffrn_reflns_av_sigmaI/netI    0.0135
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       10
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1818
_diffrn_reflns_theta_max         48.03
_diffrn_reflns_theta_min         7.80
_exptl_absorpt_coefficient_mu    '2.610, at 1 Angstrom'
_exptl_absorpt_correction_T_max  0.64
_exptl_absorpt_correction_T_min  0.26
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
;
The linear absorption coefficient is wavelength dependent
and it is calculated as:
mu = 1.34 + 1.27 * lambda [cm^-1]
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.371
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'irregular prism'
_exptl_crystal_F_000             5.87
_exptl_crystal_size_max          3.0
_exptl_crystal_size_mid          3.0
_exptl_crystal_size_min          2.0
_refine_ls_extinction_coef       0.042
_refine_ls_extinction_method     'Becker-Coppens Lorentzian model'
_refine_ls_goodness_of_fit_ref   2.143
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     119
_refine_ls_number_reflns         836
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      2.143
_refine_ls_R_factor_all          0.0844
_refine_ls_R_factor_gt           0.0844
_refine_ls_shift/su_max          0.003
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2079
_refine_ls_wR_factor_ref         0.2079
_reflns_number_gt                836
_reflns_number_total             836
_reflns_threshold_expression     >2sigma(I)
_cod_database_code               7050082