How do I create an AWS Cloudwatch Alarm using multiple dimensions

Maybe this works in bash as documented, but I am using powershell and windows...

I tried using json as described in the docs, but get the error:

Error parsing parameter '--dimensions': Invalid JSON: Expecting property name enclosed in double quotes

After an inordinate amount of time attempting to determine the correct syntax, this works:

--dimensions '[{\"Name\":\"instance\",\"Value\":\"Z:\"},{\"Name\":\"InstanceId\",\"Value\":\"i-xxxxxxxxx\"},{\"Name\":\"objectname\",\"Value\":\"LogicalDisk\"}]'

Apparantly when passing json, " needs to be passed as "

The following creates LogicalDisk % Free Space alarms for all the volumes in my environment:

$NAMESPACE = "CWAgent"
$METRIC_NAME =  "LogicalDisk % Free Space"
$RESULT = aws cloudwatch list-metrics --namespace $NAMESPACE --metric-name  $METRIC_NAME
$METRICS = $RESULT | ConvertFrom-Json 

$ALARM_NAME = "LogicalDisk Free Space < 25% (i-07eef2fd07e336ddb)"
$ALARM_DESCRIPTION = "Triggers if Free Disk Space is below 25%"


foreach ($METRIC in $METRICS.Metrics)
{
      $INSTANCE = $METRIC.Dimensions | Where-Object { ($_.Name -eq 'instance')}

      if ($null -ne $INSTANCE ) {
         $ALARM_DIMENSIONS = $METRIC.Dimensions | Where-Object { ($_.Name -eq 'instance') -or ($_.Name -eq 'InstanceId') -or ($_.Name -eq 'objectname')}
         $json = $ALARM_DIMENSIONS | ConvertTo-Json -Compress
         $json = $json.Replace("""","\""")  #Need to fix Syntax w '\'

         aws cloudwatch put-metric-alarm `
            --alarm-name $ALARM_NAME `
            --alarm-description $ALARM_DESCRIPTION `
            --namespace $NAMESPACE `
            --metric-name $METRIC_NAME `
            --statistic "Average" `
            --period 300 `
            --evaluation-periods 1 `
            --threshold 25 `
            --comparison-operator "LessThanThreshold" `
            --dimensions $json `
            --no-actions-enabled
      }
}