PROC-NAME: CRYSS02 Type_3

PURPOSE: To check that the values of _exptl_crystal_size_* are not larger than expected.

PROCEDURE:

(1) IF _exptl_crystal_size_min > 0.6 && _diffrn_radiation_type != neutron

issue ALERT B

? ? ? ?? "Alert B The value of _exptl_crystal_size_min is > 0.6"

(2) IF _exptl_crystal_size_mid > 0.8 && _diffrn_radiation_type != neutron

issue ALERT B

? ? ? ?? "Alert B The value of _exptl_crystal_size_mid is > 0.8"

(3) IF _exptl_crystal_size_max > 1.0 && _diffrn_radiation_type != neutron

issue ALERT B

? ? ? ?? "Alert B The value of _exptl_crystal_size_max is > 1.0"

? ? ? The crystal must be smaller than size of the incident beam at the crystal. For most diffractometers with fine-focus X-ray tubes and monochromated radiation, this size is unlikely to be much greater than 0.5 mm. Note that increasing the collimator diameter will not necessarily increase the size of the incident beam at the crystal. If the crystal used in the data collection is larger than the incident beam, then unpredictable errors in intensities will occur due to the varying amounts of the crystal in the beam for different reflection positions.?If you obtain an alert about crystal size, then data should be collected with a smaller crystal. For the above reasons, it is recommended that crystals be generally smaller than 0.5 mm along any edge.

? ? ? If you used neutrons and obtained an alert about the crystal size, then you have forgotten to set _diffrn_radiation_type 'neutron'.

(http://journals.iucr.org/services/cif/checking/CRYSS_02.html)

目的：檢查_(kāi)exptl_crystal_size_*的值是否超出預(yù)期。

過(guò)程：

(1)若_exptl_crystal_size_min > 0.6且_diffrn_radiation_type不為neutron

則發(fā)布B級(jí)警告

? ? ? ?? "Alert B The value of _exptl_crystal_size_min is > 0.6"

(2)若_exptl_crystal_size_mid > 0.8且_diffrn_radiation_type 不為 neutron

則發(fā)布B級(jí)警告

? ? ? ? ?"Alert B The value of _exptl_crystal_size_mid is > 0.8"

(3)若_exptl_crystal_size_max > 1.0且_diffrn_radiation_type不為neutron

則發(fā)布B級(jí)警告

? ? ? ?? "Alert B The value of _exptl_crystal_size_max is > 1.0"

? ? ? ? 晶體必須小于晶體上入射光束的大小。對(duì)于大多數(shù)具有精細(xì)聚焦X射線管和單色輻射的衍射儀，該尺寸不太可能遠(yuǎn)大于0.5 mm。注意，增加準(zhǔn)直器直徑不一定會(huì)增加晶體處入射光束的尺寸。若數(shù)據(jù)收集中使用的晶體大于入射光束，則由于光束中不同衍射位置的晶體數(shù)量的變化，強(qiáng)度上會(huì)發(fā)生不可預(yù)測(cè)的誤差。若出現(xiàn)關(guān)于晶體尺寸的警告，則應(yīng)當(dāng)使用較小的晶體收集數(shù)據(jù)。由于上述原因，建議晶體的任何邊緣通常小于0.5 mm。

? ? ? ? 若你使用中子衍射收集數(shù)據(jù)的數(shù)據(jù)出現(xiàn)晶體尺寸警告，那么想必你是忘了將_diffrn_radiation_type設(shè)為“neutron”。

警告原因：晶體尺寸超出限制大小。

解決策略：將晶體尺寸改為合適的數(shù)值。